diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
index 994b4b052cc5..18f08644e0ac 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
@@ -661,6 +661,8 @@ private void processJVMKtorLibrary(final String infrastructureFolder) {
         supportingFiles.add(new SupportingFile("infrastructure/ApiAbstractions.kt.mustache", infrastructureFolder, "ApiAbstractions.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/ApiClient.kt.mustache", infrastructureFolder, "ApiClient.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/HttpResponse.kt.mustache", infrastructureFolder, "HttpResponse.kt"));
+        supportingFiles.add(new SupportingFile("infrastructure/HttpResponseExtensions.kt.mustache", infrastructureFolder, "HttpResponseExtensions.kt"));
+        supportingFiles.add(new SupportingFile("infrastructure/Errors.kt.mustache", infrastructureFolder, "Errors.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/RequestConfig.kt.mustache", infrastructureFolder, "RequestConfig.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/RequestMethod.kt.mustache", infrastructureFolder, "RequestMethod.kt"));
 
@@ -669,6 +671,8 @@ private void processJVMKtorLibrary(final String infrastructureFolder) {
         supportingFiles.add(new SupportingFile("auth/HttpBasicAuth.kt.mustache", authFolder, "HttpBasicAuth.kt"));
         supportingFiles.add(new SupportingFile("auth/HttpBearerAuth.kt.mustache", authFolder, "HttpBearerAuth.kt"));
         supportingFiles.add(new SupportingFile("auth/OAuth.kt.mustache", authFolder, "OAuth.kt"));
+
+        addSupportingSerializerAdapters(infrastructureFolder);
     }
 
     /**
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
index 51eda6573dc7..dc699ead5826 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
@@ -53,7 +53,6 @@ apply plugin: 'kotlinx-serialization'
 {{#idea}}
 apply plugin: 'idea'
 {{/idea}}
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
@@ -113,6 +112,7 @@ dependencies {
     implementation "io.ktor:ktor-client-jackson:$ktor_version"
     implementation "io.ktor:ktor-serialization-jackson:$ktor_version"
     {{/jackson}}
+    implementation "io.ktor:ktor-client-cio:$ktor_version"
     {{/jvm-ktor}}
     {{#jvm-okhttp3}}
     implementation "com.squareup.okhttp3:okhttp:3.12.13"
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/OffsetDateTimeAdapter.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/OffsetDateTimeAdapter.kt.mustache
index fff7ded5c28d..a36c5cfdb090 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/OffsetDateTimeAdapter.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/OffsetDateTimeAdapter.kt.mustache
@@ -38,9 +38,22 @@ import org.threeten.bp.format.DateTimeFormatter
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
 {{/moshi}}
 {{#gson}}
@@ -58,16 +71,28 @@ import org.threeten.bp.format.DateTimeFormatter
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
 {{/gson}}
 {{#kotlinx_serialization}}
@@ -80,7 +105,21 @@ import org.threeten.bp.format.DateTimeFormatter
     }
 
     override fun deserialize(decoder: Decoder): OffsetDateTime {
-        return OffsetDateTime.parse(decoder.decodeString(), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(decoder.decodeString()), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
     }
 }
 {{/kotlinx_serialization}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/ApiClient.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/ApiClient.kt.mustache
index 301af9194f8c..369c3740e7f8 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/ApiClient.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/ApiClient.kt.mustache
@@ -21,10 +21,14 @@ import io.ktor.http.content.PartData
 import io.ktor.http.encodeURLQueryComponent
 import io.ktor.http.encodedPath
 import io.ktor.http.takeFrom
+import io.ktor.http.ContentType.Application
 {{#gson}}
 import io.ktor.serialization.gson.*
 import com.google.gson.GsonBuilder
 import java.text.DateFormat
+import java.time.LocalDate
+import java.time.LocalDateTime
+import java.time.OffsetDateTime
 {{/gson}}
 {{#jackson}}
 import io.ktor.serialization.jackson.*
@@ -85,6 +89,10 @@ import {{packageName}}.auth.*
         {{#gson}}
           val JSON_DEFAULT : GsonBuilder.() -> Unit = {
             setDateFormat(DateFormat.LONG)
+            registerTypeAdapter(OffsetDateTime::class.java, OffsetDateTimeAdapter())
+            registerTypeAdapter(LocalDateTime::class.java, LocalDateTimeAdapter())
+            registerTypeAdapter(LocalDate::class.java, LocalDateAdapter())
+            registerTypeAdapter(ByteArray::class.java, ByteArrayAdapter())
             setPrettyPrinting()
           }
         {{/gson}}
@@ -196,6 +204,7 @@ import {{packageName}}.auth.*
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 setBody(body)
             }
         }
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/Errors.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/Errors.kt.mustache
new file mode 100644
index 000000000000..562ca591330e
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/Errors.kt.mustache
@@ -0,0 +1,18 @@
+@file:Suppress("unused")
+package {{packageName}}.infrastructure
+
+import java.lang.RuntimeException
+
+{{#nonPublicApi}}internal {{/nonPublicApi}}open class ClientException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    {{#nonPublicApi}}internal {{/nonPublicApi}}companion object {
+        private const val serialVersionUID: Long = 123L
+    }
+}
+
+{{#nonPublicApi}}internal {{/nonPublicApi}}open class ServerException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    {{#nonPublicApi}}internal {{/nonPublicApi}}companion object {
+        private const val serialVersionUID: Long = 456L
+    }
+}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponse.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponse.kt.mustache
index 87a68f3084e5..edf91f4de2e1 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponse.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponse.kt.mustache
@@ -2,8 +2,11 @@ package {{packageName}}.infrastructure
 
 import io.ktor.http.Headers
 import io.ktor.http.isSuccess
+import io.ktor.util.InternalAPI
 import io.ktor.util.reflect.TypeInfo
 import io.ktor.util.reflect.typeInfo
+import io.ktor.utils.io.readUTF8Line
+
 
 {{#nonPublicApi}}internal {{/nonPublicApi}}open class HttpResponse<T : Any>(val response: io.ktor.client.statement.HttpResponse, val provider: BodyProvider<T>) {
     val status: Int = response.status.value
@@ -26,10 +29,15 @@ import io.ktor.util.reflect.typeInfo
     suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V
 }
 
+@OptIn(InternalAPI::class)
 {{#nonPublicApi}}internal {{/nonPublicApi}}class TypedBodyProvider<T : Any>(private val type: TypeInfo) : BodyProvider<T> {
     @Suppress("UNCHECKED_CAST")
-    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T =
-            response.call.body(type) as T
+    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T = when {
+        response.status.isSuccess() -> response.call.body(type) as T
+        response.isClientError -> throw ClientException("Client error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        response.isServerError -> throw ServerException("Server error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        else -> throw RuntimeException()
+    }
 
     @Suppress("UNCHECKED_CAST")
     override suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V =
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponseExtensions.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponseExtensions.kt.mustache
new file mode 100644
index 000000000000..e3525dedfc32
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-ktor/infrastructure/HttpResponseExtensions.kt.mustache
@@ -0,0 +1,24 @@
+package {{packageName}}.infrastructure
+
+import io.ktor.client.statement.HttpResponse
+
+/**
+ * Provides an extension to evaluation whether the response is a 1xx code
+ */
+{{#nonPublicApi}}internal {{/nonPublicApi}}val HttpResponse.isInformational : Boolean get() = this.status.value in 100..199
+
+/**
+ * Provides an extension to evaluation whether the response is a 3xx code
+ */
+@Suppress("EXTENSION_SHADOWED_BY_MEMBER")
+{{#nonPublicApi}}internal {{/nonPublicApi}}val HttpResponse.isRedirect : Boolean get() = this.status.value in 300..399
+
+/**
+ * Provides an extension to evaluation whether the response is a 4xx code
+ */
+{{#nonPublicApi}}internal {{/nonPublicApi}}val HttpResponse.isClientError : Boolean get() = this.status.value in 400..499
+
+/**
+ * Provides an extension to evaluation whether the response is a 5xx (Standard) through 9999 (non-standard) code
+ */
+{{#nonPublicApi}}internal {{/nonPublicApi}}val HttpResponse.isServerError : Boolean get() = this.status.value in 500..9999
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
index 5c467a1b8843..f0ce5e9d76a2 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
@@ -143,11 +143,11 @@ import {{packageName}}.infrastructure.toMultiValue
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/infrastructure/ApiClient.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/infrastructure/ApiClient.kt.mustache
index bbed97d77aed..6118da3fd7b8 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/infrastructure/ApiClient.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/infrastructure/ApiClient.kt.mustache
@@ -12,6 +12,7 @@ import io.ktor.client.request.parameter
 import io.ktor.client.statement.HttpResponse
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.http.*
+import io.ktor.http.ContentType.Application
 import io.ktor.http.content.PartData
 import kotlin.Unit
 import kotlinx.serialization.json.Json
@@ -154,6 +155,7 @@ import {{packageName}}.auth.*
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 this.setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-allOff-discriminator/build.gradle b/samples/client/petstore/kotlin-allOff-discriminator/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-allOff-discriminator/build.gradle
+++ b/samples/client/petstore/kotlin-allOff-discriminator/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-allOff-discriminator/gradlew b/samples/client/petstore/kotlin-allOff-discriminator/gradlew
old mode 100644
new mode 100755
diff --git a/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/apis/BirdApi.kt b/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/apis/BirdApi.kt
index 84f087c90b26..5cf2c0028e43 100644
--- a/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/apis/BirdApi.kt
+++ b/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/apis/BirdApi.kt
@@ -67,11 +67,11 @@ class BirdApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-allOff-discriminator/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/build.gradle b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/build.gradle
index 3822ee114c79..759f2a40b5bf 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/build.gradle
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index f25a3c0953c9..6fe15e7f0997 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -65,11 +65,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/build.gradle b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/build.gradle
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index 9e3ae5ca5acd..8e6aa49a3d90 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -65,11 +65,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-array-simple-string-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-array-simple-string-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-array-simple-string-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-array-simple-string-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-array-simple-string-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index 529ae1e4d05f..2c28c43be55e 100644
--- a/samples/client/petstore/kotlin-array-simple-string-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-array-simple-string-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,6 +12,7 @@ import io.ktor.client.request.parameter
 import io.ktor.client.statement.HttpResponse
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.http.*
+import io.ktor.http.ContentType.Application
 import io.ktor.http.content.PartData
 import kotlin.Unit
 import kotlinx.serialization.json.Json
@@ -143,6 +144,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 this.setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-bigdecimal-default-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-bigdecimal-default-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index 529ae1e4d05f..2c28c43be55e 100644
--- a/samples/client/petstore/kotlin-bigdecimal-default-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-bigdecimal-default-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,6 +12,7 @@ import io.ktor.client.request.parameter
 import io.ktor.client.statement.HttpResponse
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.http.*
+import io.ktor.http.ContentType.Application
 import io.ktor.http.content.PartData
 import kotlin.Unit
 import kotlinx.serialization.json.Json
@@ -143,6 +144,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 this.setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/build.gradle b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/build.gradle
+++ b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index c1323d49b089..36c910b34f19 100644
--- a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -66,11 +66,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-bigdecimal-default-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/build.gradle b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/build.gradle
index 3822ee114c79..759f2a40b5bf 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/build.gradle
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index e5342a3c2fd3..af7cced0c6c2 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -93,11 +93,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/build.gradle b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/build.gradle
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index bf0058dc6cd0..dea3f44c24b7 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -93,11 +93,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-okhttp4/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-retrofit2/build.gradle b/samples/client/petstore/kotlin-default-values-jvm-retrofit2/build.gradle
index a72e41c6d372..91745c4f63aa 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-retrofit2/build.gradle
+++ b/samples/client/petstore/kotlin-default-values-jvm-retrofit2/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-default-values-jvm-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-default-values-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-default-values-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-default-values-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-default-values-jvm-volley/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-default-values-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-default-values-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index 529ae1e4d05f..2c28c43be55e 100644
--- a/samples/client/petstore/kotlin-default-values-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-default-values-multiplatform/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,6 +12,7 @@ import io.ktor.client.request.parameter
 import io.ktor.client.statement.HttpResponse
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.http.*
+import io.ktor.http.ContentType.Application
 import io.ktor.http.content.PartData
 import kotlin.Unit
 import kotlinx.serialization.json.Json
@@ -143,6 +144,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 this.setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-enum-default-value/build.gradle b/samples/client/petstore/kotlin-enum-default-value/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-enum-default-value/build.gradle
+++ b/samples/client/petstore/kotlin-enum-default-value/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index e70279d32c97..0e15c705b001 100644
--- a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -66,11 +66,11 @@ class DefaultApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-gson/build.gradle b/samples/client/petstore/kotlin-gson/build.gradle
index fb0b38ea3426..433706ed2164 100644
--- a/samples/client/petstore/kotlin-gson/build.gradle
+++ b/samples/client/petstore/kotlin-gson/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 242cfabd72ef..f2fd3a83a3e8 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 78a5eefbab42..899762cba18f 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 5a3088e0f2c4..d66c5a06e69d 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-jackson/build.gradle b/samples/client/petstore/kotlin-jackson/build.gradle
index 73ef0b01c56b..8aff3040b408 100644
--- a/samples/client/petstore/kotlin-jackson/build.gradle
+++ b/samples/client/petstore/kotlin-jackson/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 2308fddead18..057e1be123f8 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index c76e8c708a55..e99a98ed0568 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index c7847514b1ac..f5d2c01b2781 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-json-request-string/build.gradle b/samples/client/petstore/kotlin-json-request-string/build.gradle
index 2e9236ca0848..f2e1ee62dd5d 100644
--- a/samples/client/petstore/kotlin-json-request-string/build.gradle
+++ b/samples/client/petstore/kotlin-json-request-string/build.gradle
@@ -21,7 +21,6 @@ buildscript {
 apply plugin: 'kotlin'
 apply plugin: 'kotlin-parcelize'
 apply plugin: 'kotlinx-serialization'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 381b2f8f1835..e7c96048ba94 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -68,11 +68,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -137,11 +137,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -210,11 +210,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -286,11 +286,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -361,11 +361,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -430,11 +430,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -500,11 +500,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -576,11 +576,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index c6cfe5c11799..86191bdbc2a6 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -67,11 +67,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -134,11 +134,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -202,11 +202,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -272,11 +272,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index e7f3e993e7b9..54e3c6b08b85 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -67,11 +67,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -134,11 +134,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -268,11 +268,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -336,11 +336,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -407,11 +407,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -481,11 +481,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -547,11 +547,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e0fe9e3b5321..8f413d36386a 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -19,6 +19,20 @@ object OffsetDateTimeAdapter : KSerializer<OffsetDateTime> {
     }
 
     override fun deserialize(decoder: Decoder): OffsetDateTime {
-        return OffsetDateTime.parse(decoder.decodeString(), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(decoder.decodeString()), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
     }
 }
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/.openapi-generator/FILES b/samples/client/petstore/kotlin-jvm-ktor-gson/.openapi-generator/FILES
index dce25d98f090..dd09e92eab84 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-gson/.openapi-generator/FILES
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/.openapi-generator/FILES
@@ -24,9 +24,16 @@ src/main/kotlin/org/openapitools/client/auth/HttpBearerAuth.kt
 src/main/kotlin/org/openapitools/client/auth/OAuth.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
 src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
+src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
+src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
 src/main/kotlin/org/openapitools/client/models/Category.kt
 src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
 src/main/kotlin/org/openapitools/client/models/Order.kt
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/build.gradle b/samples/client/petstore/kotlin-jvm-ktor-gson/build.gradle
index ab8fa9dbf3e4..28ff0043887d 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-gson/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
@@ -36,5 +35,6 @@ dependencies {
     implementation "io.ktor:ktor-client-content-negotiation:$ktor_version"
     implementation "io.ktor:ktor-serialization-gson:$ktor_version"
     implementation "io.ktor:ktor-client-gson:$ktor_version"
+    implementation "io.ktor:ktor-client-cio:$ktor_version"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.4.2"
 }
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index 69c803dfbcf6..5fc90ddd30e2 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -21,9 +21,13 @@ import io.ktor.http.content.PartData
 import io.ktor.http.encodeURLQueryComponent
 import io.ktor.http.encodedPath
 import io.ktor.http.takeFrom
+import io.ktor.http.ContentType.Application
 import io.ktor.serialization.gson.*
 import com.google.gson.GsonBuilder
 import java.text.DateFormat
+import java.time.LocalDate
+import java.time.LocalDateTime
+import java.time.OffsetDateTime
 import org.openapitools.client.auth.*
 
 open class ApiClient(
@@ -56,6 +60,10 @@ open class ApiClient(
           const val BASE_URL = "http://petstore.swagger.io/v2"
           val JSON_DEFAULT : GsonBuilder.() -> Unit = {
             setDateFormat(DateFormat.LONG)
+            registerTypeAdapter(OffsetDateTime::class.java, OffsetDateTimeAdapter())
+            registerTypeAdapter(LocalDateTime::class.java, LocalDateTimeAdapter())
+            registerTypeAdapter(LocalDate::class.java, LocalDateAdapter())
+            registerTypeAdapter(ByteArray::class.java, ByteArrayAdapter())
             setPrettyPrinting()
           }
           protected val UNSAFE_HEADERS = listOf(HttpHeaders.ContentType)
@@ -156,6 +164,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
new file mode 100644
index 000000000000..6120b081929d
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
@@ -0,0 +1,33 @@
+package org.openapitools.client.infrastructure
+
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import com.google.gson.stream.JsonToken.NULL
+import java.io.IOException
+
+class ByteArrayAdapter : TypeAdapter<ByteArray>() {
+    @Throws(IOException::class)
+    override fun write(out: JsonWriter?, value: ByteArray?) {
+        if (value == null) {
+            out?.nullValue()
+        } else {
+            out?.value(String(value))
+        }
+    }
+
+    @Throws(IOException::class)
+    override fun read(out: JsonReader?): ByteArray? {
+        out ?: return null
+
+        when (out.peek()) {
+            NULL -> {
+                out.nextNull()
+                return null
+            }
+            else -> {
+                return out.nextString().toByteArray()
+            }
+        }
+    }
+}
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
new file mode 100644
index 000000000000..ec06b52ec8cf
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
@@ -0,0 +1,18 @@
+@file:Suppress("unused")
+package org.openapitools.client.infrastructure
+
+import java.lang.RuntimeException
+
+open class ClientException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    companion object {
+        private const val serialVersionUID: Long = 123L
+    }
+}
+
+open class ServerException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    companion object {
+        private const val serialVersionUID: Long = 456L
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
index 4285d605ea62..e4a1bc6f0b5b 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
@@ -2,8 +2,11 @@ package org.openapitools.client.infrastructure
 
 import io.ktor.http.Headers
 import io.ktor.http.isSuccess
+import io.ktor.util.InternalAPI
 import io.ktor.util.reflect.TypeInfo
 import io.ktor.util.reflect.typeInfo
+import io.ktor.utils.io.readUTF8Line
+
 
 open class HttpResponse<T : Any>(val response: io.ktor.client.statement.HttpResponse, val provider: BodyProvider<T>) {
     val status: Int = response.status.value
@@ -26,10 +29,15 @@ interface BodyProvider<T : Any> {
     suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V
 }
 
+@OptIn(InternalAPI::class)
 class TypedBodyProvider<T : Any>(private val type: TypeInfo) : BodyProvider<T> {
     @Suppress("UNCHECKED_CAST")
-    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T =
-            response.call.body(type) as T
+    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T = when {
+        response.status.isSuccess() -> response.call.body(type) as T
+        response.isClientError -> throw ClientException("Client error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        response.isServerError -> throw ServerException("Server error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        else -> throw RuntimeException()
+    }
 
     @Suppress("UNCHECKED_CAST")
     override suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V =
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
new file mode 100644
index 000000000000..02274d4195a1
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
@@ -0,0 +1,24 @@
+package org.openapitools.client.infrastructure
+
+import io.ktor.client.statement.HttpResponse
+
+/**
+ * Provides an extension to evaluation whether the response is a 1xx code
+ */
+val HttpResponse.isInformational : Boolean get() = this.status.value in 100..199
+
+/**
+ * Provides an extension to evaluation whether the response is a 3xx code
+ */
+@Suppress("EXTENSION_SHADOWED_BY_MEMBER")
+val HttpResponse.isRedirect : Boolean get() = this.status.value in 300..399
+
+/**
+ * Provides an extension to evaluation whether the response is a 4xx code
+ */
+val HttpResponse.isClientError : Boolean get() = this.status.value in 400..499
+
+/**
+ * Provides an extension to evaluation whether the response is a 5xx (Standard) through 9999 (non-standard) code
+ */
+val HttpResponse.isServerError : Boolean get() = this.status.value in 500..9999
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
new file mode 100644
index 000000000000..30ef6697183a
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
@@ -0,0 +1,35 @@
+package org.openapitools.client.infrastructure
+
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import com.google.gson.stream.JsonToken.NULL
+import java.io.IOException
+import java.time.LocalDate
+import java.time.format.DateTimeFormatter
+
+class LocalDateAdapter(private val formatter: DateTimeFormatter = DateTimeFormatter.ISO_LOCAL_DATE) : TypeAdapter<LocalDate>() {
+    @Throws(IOException::class)
+    override fun write(out: JsonWriter?, value: LocalDate?) {
+        if (value == null) {
+            out?.nullValue()
+        } else {
+            out?.value(formatter.format(value))
+        }
+    }
+
+    @Throws(IOException::class)
+    override fun read(out: JsonReader?): LocalDate? {
+        out ?: return null
+
+        when (out.peek()) {
+            NULL -> {
+                out.nextNull()
+                return null
+            }
+            else -> {
+                return LocalDate.parse(out.nextString(), formatter)
+            }
+        }
+    }
+}
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
new file mode 100644
index 000000000000..3ad781c66ca1
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
@@ -0,0 +1,35 @@
+package org.openapitools.client.infrastructure
+
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import com.google.gson.stream.JsonToken.NULL
+import java.io.IOException
+import java.time.LocalDateTime
+import java.time.format.DateTimeFormatter
+
+class LocalDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeFormatter.ISO_LOCAL_DATE_TIME) : TypeAdapter<LocalDateTime>() {
+    @Throws(IOException::class)
+    override fun write(out: JsonWriter?, value: LocalDateTime?) {
+        if (value == null) {
+            out?.nullValue()
+        } else {
+            out?.value(formatter.format(value))
+        }
+    }
+
+    @Throws(IOException::class)
+    override fun read(out: JsonReader?): LocalDateTime? {
+        out ?: return null
+
+        when (out.peek()) {
+            NULL -> {
+                out.nextNull()
+                return null
+            }
+            else -> {
+                return LocalDateTime.parse(out.nextString(), formatter)
+            }
+        }
+    }
+}
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
new file mode 100644
index 000000000000..afe8b8489462
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -0,0 +1,47 @@
+package org.openapitools.client.infrastructure
+
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
+import com.google.gson.stream.JsonToken.NULL
+import java.io.IOException
+import java.time.OffsetDateTime
+import java.time.format.DateTimeFormatter
+
+class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME) : TypeAdapter<OffsetDateTime>() {
+    @Throws(IOException::class)
+    override fun write(out: JsonWriter?, value: OffsetDateTime?) {
+        if (value == null) {
+            out?.nullValue()
+        } else {
+            out?.value(formatter.format(value))
+        }
+    }
+
+    @Throws(IOException::class)
+    override fun read(out: JsonReader?): OffsetDateTime? {
+        out ?: return null
+
+        return when (out.peek()) {
+            NULL -> {
+                out.nextNull()
+                return null
+            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
+}
diff --git a/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
new file mode 100644
index 000000000000..6e16e4f6582b
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-gson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -0,0 +1,22 @@
+package org.openapitools.client.infrastructure
+
+import com.google.gson.Gson
+import com.google.gson.GsonBuilder
+import java.time.LocalDate
+import java.time.LocalDateTime
+import java.time.OffsetDateTime
+import java.util.UUID
+
+object Serializer {
+    @JvmStatic
+    val gsonBuilder: GsonBuilder = GsonBuilder()
+        .registerTypeAdapter(OffsetDateTime::class.java, OffsetDateTimeAdapter())
+        .registerTypeAdapter(LocalDateTime::class.java, LocalDateTimeAdapter())
+        .registerTypeAdapter(LocalDate::class.java, LocalDateAdapter())
+        .registerTypeAdapter(ByteArray::class.java, ByteArrayAdapter())
+
+    @JvmStatic
+    val gson: Gson by lazy {
+        gsonBuilder.create()
+    }
+}
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/.openapi-generator/FILES b/samples/client/petstore/kotlin-jvm-ktor-jackson/.openapi-generator/FILES
index dce25d98f090..c473fd51458b 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/.openapi-generator/FILES
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/.openapi-generator/FILES
@@ -24,9 +24,12 @@ src/main/kotlin/org/openapitools/client/auth/HttpBearerAuth.kt
 src/main/kotlin/org/openapitools/client/auth/OAuth.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
 src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
+src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
 src/main/kotlin/org/openapitools/client/models/Category.kt
 src/main/kotlin/org/openapitools/client/models/ModelApiResponse.kt
 src/main/kotlin/org/openapitools/client/models/Order.kt
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/build.gradle b/samples/client/petstore/kotlin-jvm-ktor-jackson/build.gradle
index 63636d11ac50..900a49345c72 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
@@ -38,5 +37,6 @@ dependencies {
     implementation "io.ktor:ktor-client-content-negotiation:$ktor_version"
     implementation "io.ktor:ktor-client-jackson:$ktor_version"
     implementation "io.ktor:ktor-serialization-jackson:$ktor_version"
+    implementation "io.ktor:ktor-client-cio:$ktor_version"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.4.2"
 }
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index bb3a5290cf6e..a86a00933ecf 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -21,6 +21,7 @@ import io.ktor.http.content.PartData
 import io.ktor.http.encodeURLQueryComponent
 import io.ktor.http.encodedPath
 import io.ktor.http.takeFrom
+import io.ktor.http.ContentType.Application
 import io.ktor.serialization.jackson.*
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.fasterxml.jackson.databind.ObjectMapper
@@ -164,6 +165,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
new file mode 100644
index 000000000000..ec06b52ec8cf
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
@@ -0,0 +1,18 @@
+@file:Suppress("unused")
+package org.openapitools.client.infrastructure
+
+import java.lang.RuntimeException
+
+open class ClientException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    companion object {
+        private const val serialVersionUID: Long = 123L
+    }
+}
+
+open class ServerException(message: kotlin.String? = null, val statusCode: Int = -1, val response: io.ktor.client.statement.HttpResponse? = null) : RuntimeException(message) {
+
+    companion object {
+        private const val serialVersionUID: Long = 456L
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
index 4285d605ea62..e4a1bc6f0b5b 100644
--- a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
@@ -2,8 +2,11 @@ package org.openapitools.client.infrastructure
 
 import io.ktor.http.Headers
 import io.ktor.http.isSuccess
+import io.ktor.util.InternalAPI
 import io.ktor.util.reflect.TypeInfo
 import io.ktor.util.reflect.typeInfo
+import io.ktor.utils.io.readUTF8Line
+
 
 open class HttpResponse<T : Any>(val response: io.ktor.client.statement.HttpResponse, val provider: BodyProvider<T>) {
     val status: Int = response.status.value
@@ -26,10 +29,15 @@ interface BodyProvider<T : Any> {
     suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V
 }
 
+@OptIn(InternalAPI::class)
 class TypedBodyProvider<T : Any>(private val type: TypeInfo) : BodyProvider<T> {
     @Suppress("UNCHECKED_CAST")
-    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T =
-            response.call.body(type) as T
+    override suspend fun body(response: io.ktor.client.statement.HttpResponse): T = when {
+        response.status.isSuccess() -> response.call.body(type) as T
+        response.isClientError -> throw ClientException("Client error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        response.isServerError -> throw ServerException("Server error : ${response.status.value} ${response.content.readUTF8Line()}", response.status.value, response)
+        else -> throw RuntimeException()
+    }
 
     @Suppress("UNCHECKED_CAST")
     override suspend fun <V : Any> typedBody(response: io.ktor.client.statement.HttpResponse, type: TypeInfo): V =
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
new file mode 100644
index 000000000000..02274d4195a1
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/HttpResponseExtensions.kt
@@ -0,0 +1,24 @@
+package org.openapitools.client.infrastructure
+
+import io.ktor.client.statement.HttpResponse
+
+/**
+ * Provides an extension to evaluation whether the response is a 1xx code
+ */
+val HttpResponse.isInformational : Boolean get() = this.status.value in 100..199
+
+/**
+ * Provides an extension to evaluation whether the response is a 3xx code
+ */
+@Suppress("EXTENSION_SHADOWED_BY_MEMBER")
+val HttpResponse.isRedirect : Boolean get() = this.status.value in 300..399
+
+/**
+ * Provides an extension to evaluation whether the response is a 4xx code
+ */
+val HttpResponse.isClientError : Boolean get() = this.status.value in 400..499
+
+/**
+ * Provides an extension to evaluation whether the response is a 5xx (Standard) through 9999 (non-standard) code
+ */
+val HttpResponse.isServerError : Boolean get() = this.status.value in 500..9999
diff --git a/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
new file mode 100644
index 000000000000..ece5c413e124
--- /dev/null
+++ b/samples/client/petstore/kotlin-jvm-ktor-jackson/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -0,0 +1,14 @@
+package org.openapitools.client.infrastructure
+
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.databind.SerializationFeature
+import com.fasterxml.jackson.annotation.JsonInclude
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+
+object Serializer {
+    @JvmStatic
+    val jacksonObjectMapper: ObjectMapper = jacksonObjectMapper()
+        .findAndRegisterModules()
+        .setSerializationInclusion(JsonInclude.Include.NON_ABSENT)
+        .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
+}
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/build.gradle b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/build.gradle
index ff5712e41186..750ca3580054 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index eecb37205f2e..b28081d91b6d 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -69,11 +69,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -138,11 +138,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -218,11 +218,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -293,11 +293,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -369,11 +369,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -438,11 +438,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -508,11 +508,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -584,11 +584,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d1f4b7975a34..0cd065d15bf4 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -68,11 +68,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -135,11 +135,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -203,11 +203,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -273,11 +273,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 0df9761bc90e..b7d73ec902f0 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -68,11 +68,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -135,11 +135,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -202,11 +202,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -269,11 +269,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -337,11 +337,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -408,11 +408,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -482,11 +482,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -548,11 +548,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-gson/build.gradle b/samples/client/petstore/kotlin-jvm-vertx-gson/build.gradle
index 42898256f39b..87adecca40d5 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-gson/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-vertx-gson/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-vertx-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-jvm-vertx-gson/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-jackson-coroutines/build.gradle b/samples/client/petstore/kotlin-jvm-vertx-jackson-coroutines/build.gradle
index a8f19fa280f4..673cb2f4dfc8 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-jackson-coroutines/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-vertx-jackson-coroutines/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-jackson/build.gradle b/samples/client/petstore/kotlin-jvm-vertx-jackson/build.gradle
index 4237826a4a66..82d9d58a79bb 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-jackson/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-vertx-jackson/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-moshi/build.gradle b/samples/client/petstore/kotlin-jvm-vertx-moshi/build.gradle
index af121477e730..815a2b9bdf03 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-moshi/build.gradle
+++ b/samples/client/petstore/kotlin-jvm-vertx-moshi/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-jvm-vertx-moshi/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-vertx-moshi/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-jvm-vertx-moshi/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-jvm-vertx-moshi/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-jvm-volley/src/main/java/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-jvm-volley/src/main/java/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e615135c9cc0..afe8b8489462 100644
--- a/samples/client/petstore/kotlin-jvm-volley/src/main/java/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-jvm-volley/src/main/java/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -22,14 +22,26 @@ class OffsetDateTimeAdapter(private val formatter: DateTimeFormatter = DateTimeF
     override fun read(out: JsonReader?): OffsetDateTime? {
         out ?: return null
 
-        when (out.peek()) {
+        return when (out.peek()) {
             NULL -> {
                 out.nextNull()
                 return null
             }
-            else -> {
-                return OffsetDateTime.parse(out.nextString(), formatter)
-            }
+            else -> OffsetDateTime.parse(tryFormatDateTime(out.nextString()), formatter)
+        }
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
         }
     }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-modelMutable/build.gradle b/samples/client/petstore/kotlin-modelMutable/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-modelMutable/build.gradle
+++ b/samples/client/petstore/kotlin-modelMutable/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 58787a00f531..a941731c02e7 100644
--- a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 49220c8b4dd2..095aacdd66ca 100644
--- a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 652c44082b2f..c0f66413a141 100644
--- a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-modelMutable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/build.gradle b/samples/client/petstore/kotlin-moshi-codegen/build.gradle
index eb1a5adf8902..177686ccbfc9 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/build.gradle
+++ b/samples/client/petstore/kotlin-moshi-codegen/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 
 apply plugin: 'kotlin'
 apply plugin: 'kotlin-kapt'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 9b1451613f0e..65955ca0f7ad 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 2184157a2ed0..52c87dd0c374 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 720713cafecb..d2d313f8900f 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index 35e549b98296..5508687fe7a5 100644
--- a/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,6 +12,7 @@ import io.ktor.client.request.parameter
 import io.ktor.client.statement.HttpResponse
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.http.*
+import io.ktor.http.ContentType.Application
 import io.ktor.http.content.PartData
 import kotlin.Unit
 import kotlinx.serialization.json.Json
@@ -147,6 +148,7 @@ open class ApiClient(
             this.method = requestConfig.method.httpMethod
             headers.filter { header -> !UNSAFE_HEADERS.contains(header.key) }.forEach { header -> this.header(header.key, header.value) }
             if (requestConfig.method in listOf(RequestMethod.PUT, RequestMethod.POST, RequestMethod.PATCH)) {
+                this.contentType(Application.Json)
                 this.setBody(body)
             }
         }
diff --git a/samples/client/petstore/kotlin-multiplatform/src/jvmTest/kotlin/util/PetShopTest.kt b/samples/client/petstore/kotlin-multiplatform/src/jvmTest/kotlin/util/PetShopTest.kt
new file mode 100644
index 000000000000..546ee939c8f6
--- /dev/null
+++ b/samples/client/petstore/kotlin-multiplatform/src/jvmTest/kotlin/util/PetShopTest.kt
@@ -0,0 +1,13 @@
+package util
+
+import org.junit.Test
+import org.openapitools.client.apis.PetApi
+import org.openapitools.client.models.Pet
+
+class PetStoreTest {
+    @Test
+    fun addPet() = runTest {
+        val mainApi = PetApi()
+        println(mainApi.addPet(Pet("TestPet", emptyList())).body())
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-nonpublic/build.gradle b/samples/client/petstore/kotlin-nonpublic/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-nonpublic/build.gradle
+++ b/samples/client/petstore/kotlin-nonpublic/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 72a5ce749c9c..d26d0e1f7575 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpC
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 4efeb8f355ca..5b6acceb8b35 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ internal class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHtt
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ internal class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHtt
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ internal class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHtt
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ internal class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHtt
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 6fbc4bbfb98a..ede7c0899b5e 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttp
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index be7703c103d2..185f55e8dbe2 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ internal class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-nullable/build.gradle b/samples/client/petstore/kotlin-nullable/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-nullable/build.gradle
+++ b/samples/client/petstore/kotlin-nullable/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 2c440b44b871..88144673c739 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index c25915eaa6fd..fcff9a8e56c9 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 0730e30aa438..41581ae54c3b 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-okhttp3/build.gradle b/samples/client/petstore/kotlin-okhttp3/build.gradle
index 3822ee114c79..759f2a40b5bf 100644
--- a/samples/client/petstore/kotlin-okhttp3/build.gradle
+++ b/samples/client/petstore/kotlin-okhttp3/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 1460cd1d977f..1b7ef12fdd56 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 8474d8e3459f..97383e2aad58 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index d35e1a9c4fc2..ebb16bdaea0d 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/build.gradle b/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/build.gradle
index f712fe610efd..4a0a28e61b8f 100644
--- a/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/build.gradle
+++ b/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/build.gradle
@@ -21,7 +21,6 @@ buildscript {
 
 apply plugin: 'kotlin'
 apply plugin: 'kotlinx-serialization'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e0fe9e3b5321..8f413d36386a 100644
--- a/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-retrofit2-kotlinx_serialization/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -19,6 +19,20 @@ object OffsetDateTimeAdapter : KSerializer<OffsetDateTime> {
     }
 
     override fun deserialize(decoder: Decoder): OffsetDateTime {
-        return OffsetDateTime.parse(decoder.decodeString(), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(decoder.decodeString()), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
     }
 }
diff --git a/samples/client/petstore/kotlin-retrofit2-rx3/build.gradle b/samples/client/petstore/kotlin-retrofit2-rx3/build.gradle
index e8c650bb0915..53ae2d6bdf36 100644
--- a/samples/client/petstore/kotlin-retrofit2-rx3/build.gradle
+++ b/samples/client/petstore/kotlin-retrofit2-rx3/build.gradle
@@ -20,7 +20,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-retrofit2-rx3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-retrofit2-rx3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-retrofit2-rx3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-retrofit2-rx3/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-retrofit2/build.gradle b/samples/client/petstore/kotlin-retrofit2/build.gradle
index bcb7ea17cf8d..95f7ab0f41ba 100644
--- a/samples/client/petstore/kotlin-retrofit2/build.gradle
+++ b/samples/client/petstore/kotlin-retrofit2/build.gradle
@@ -19,7 +19,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-retrofit2/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-string/build.gradle b/samples/client/petstore/kotlin-string/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin-string/build.gradle
+++ b/samples/client/petstore/kotlin-string/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 672d8b295d8e..46e319cc8b1d 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 2184157a2ed0..52c87dd0c374 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 720713cafecb..d2d313f8900f 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-threetenbp/build.gradle b/samples/client/petstore/kotlin-threetenbp/build.gradle
index e0c1cb3746e7..76b5e18fa59f 100644
--- a/samples/client/petstore/kotlin-threetenbp/build.gradle
+++ b/samples/client/petstore/kotlin-threetenbp/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 9b1451613f0e..65955ca0f7ad 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 2184157a2ed0..52c87dd0c374 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 720713cafecb..d2d313f8900f 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 28b3eb3cd70a..c5afffa3e279 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin-uppercase-enum/build.gradle b/samples/client/petstore/kotlin-uppercase-enum/build.gradle
index c0b73efde8e0..6b97e54c1bdf 100644
--- a/samples/client/petstore/kotlin-uppercase-enum/build.gradle
+++ b/samples/client/petstore/kotlin-uppercase-enum/build.gradle
@@ -20,7 +20,6 @@ buildscript {
 
 apply plugin: 'kotlin'
 apply plugin: 'kotlinx-serialization'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
index 3e4079f63266..722f3a79db5c 100644
--- a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
+++ b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
@@ -67,11 +67,11 @@ class EnumApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index e0fe9e3b5321..8f413d36386a 100644
--- a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -19,6 +19,20 @@ object OffsetDateTimeAdapter : KSerializer<OffsetDateTime> {
     }
 
     override fun deserialize(decoder: Decoder): OffsetDateTime {
-        return OffsetDateTime.parse(decoder.decodeString(), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(decoder.decodeString()), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+    }
+
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
     }
 }
diff --git a/samples/client/petstore/kotlin/build.gradle b/samples/client/petstore/kotlin/build.gradle
index 66a3c68b8901..43b2b3fa4273 100644
--- a/samples/client/petstore/kotlin/build.gradle
+++ b/samples/client/petstore/kotlin/build.gradle
@@ -18,7 +18,6 @@ buildscript {
 }
 
 apply plugin: 'kotlin'
-apply plugin: 'maven-publish'
 
 repositories {
     maven { url "https://repo1.maven.org/maven2" }
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 9b1451613f0e..65955ca0f7ad 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -67,11 +67,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -136,11 +136,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -216,11 +216,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -291,11 +291,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -367,11 +367,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -436,11 +436,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -506,11 +506,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -582,11 +582,11 @@ class PetApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient = A
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 2184157a2ed0..52c87dd0c374 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -66,11 +66,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -201,11 +201,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -271,11 +271,11 @@ class StoreApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 720713cafecb..d2d313f8900f 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -66,11 +66,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -133,11 +133,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -200,11 +200,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -267,11 +267,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -335,11 +335,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -406,11 +406,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -480,11 +480,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
@@ -546,11 +546,11 @@ class UserApi(basePath: kotlin.String = defaultBasePath, client: OkHttpClient =
             ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
             ResponseType.ClientError -> {
                 val localVarError = localVarResponse as ClientError<*>
-                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ClientException("Client error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
             ResponseType.ServerError -> {
                 val localVarError = localVarResponse as ServerError<*>
-                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.message.orEmpty()}", localVarError.statusCode, localVarResponse)
+                throw ServerException("Server error : ${localVarError.statusCode} ${localVarError.body}", localVarError.statusCode, localVarResponse)
             }
         }
     }
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
index 87437871a31e..2e7934045818 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/infrastructure/OffsetDateTimeAdapter.kt
@@ -13,7 +13,20 @@ class OffsetDateTimeAdapter {
 
     @FromJson
     fun fromJson(value: String): OffsetDateTime {
-        return OffsetDateTime.parse(value, DateTimeFormatter.ISO_OFFSET_DATE_TIME)
+        return OffsetDateTime.parse(tryFormatDateTime(value), DateTimeFormatter.ISO_OFFSET_DATE_TIME)
     }
 
+    private fun tryFormatDateTime(stringValue: String): String {
+        val offset = stringValue.substringAfter("+")
+        return when (offset.length) {
+            4 -> fixOffsetValue(stringValue, offset)
+            else -> stringValue
+        }
+    }
+
+    private fun fixOffsetValue(stringValue: String = "0000", offset: String): String  {
+        val offsetChars = offset.toCharArray().toMutableList()
+        offsetChars.add(2, ':')
+        return stringValue.replaceAfter("+", offsetChars.joinToString(""))
+    }
 }
diff --git a/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/PetApiTest.kt b/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/PetApiTest.kt
deleted file mode 100644
index 5da4f9082a8d..000000000000
--- a/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/PetApiTest.kt
+++ /dev/null
@@ -1,104 +0,0 @@
-package org.openapitools.client
-
-import io.kotlintest.shouldBe
-import io.kotlintest.matchers.numerics.shouldBeGreaterThan
-import io.kotlintest.matchers.string.shouldContain
-import io.kotlintest.shouldThrow
-import io.kotlintest.specs.ShouldSpec
-import org.openapitools.client.apis.PetApi
-import org.openapitools.client.infrastructure.ClientException
-import org.openapitools.client.models.Category
-import org.openapitools.client.models.Pet
-import org.openapitools.client.models.Tag
-
-class PetApiTest : ShouldSpec() {
-    init {
-
-        val petId:Long = 10006
-        val api = PetApi()
-
-        should("add a pet") {
-
-            val pet = Pet(
-                    id = petId,
-                    name = "kotlin client test",
-                    photoUrls = listOf("http://test_kotlin_unit_test.com"),
-                    category = Category(petId, "test kotlin category"),
-                    tags = listOf(Tag(petId, "test kotlin tag"))
-            )
-            api.addPet(pet)
-
-        }
-
-        should("get pet by id") {
-            val result = api.getPetById(petId)
-
-            result.id shouldBe (petId)
-            result.name shouldBe ("kotlin client test")
-            result.photoUrls[0] shouldBe ("http://test_kotlin_unit_test.com")
-            result.category!!.id shouldBe (petId)
-            result.category!!.name shouldBe ("test kotlin category")
-            result.tags!![0].id shouldBe (petId)
-            result.tags!![0].name shouldBe ("test kotlin tag")
-
-        }
-
-        should("find pet by status") {
-            val result = api.findPetsByStatus(listOf("available"))
-
-            result.size.shouldBeGreaterThan(0)
-
-            for(onePet in result) {
-                onePet.status.shouldBe(Pet.Status.available)
-            }
-
-            val result2 = api.findPetsByStatus(listOf("unknown_and_incorrect_status"))
-
-            result2.size.shouldBe(0)
-
-        }
-
-        should("update a pet") {
-            val pet = Pet(
-                    id = petId,
-                    name = "kotlin client updatePet",
-                    status = Pet.Status.pending,
-                    photoUrls = listOf("http://test_kotlin_unit_test.com")
-            )
-            api.updatePet(pet)
-
-            // verify updated Pet
-            val result = api.getPetById(petId)
-            result.id shouldBe (petId)
-            result.name shouldBe ("kotlin client updatePet")
-            result.status shouldBe (Pet.Status.pending)
-
-        }
-
-        should("update a pet with form") {
-            val name = "kotlin client updatePet with Form"
-            val status = "pending"
-
-            api.updatePetWithForm(petId, name, status)
-
-            // verify updated Pet
-            val result = api.getPetById(petId)
-            result.id shouldBe (petId)
-            result.name shouldBe ("kotlin client updatePet with Form")
-            result.status shouldBe (Pet.Status.pending)
-
-        }
-
-        should("delete a pet") {
-            api.deletePet(petId, "apiKey")
-
-            // verify updated Pet
-            val exception = shouldThrow<ClientException> {
-                api.getPetById(petId)
-            }
-            exception.message?.shouldContain("Pet not found")
-        }
-
-    }
-
-}
diff --git a/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/StoreApiTest.kt b/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/StoreApiTest.kt
deleted file mode 100644
index 8c57ecf76147..000000000000
--- a/samples/client/petstore/kotlin/src/test/kotlin/org/openapitools/client/StoreApiTest.kt
+++ /dev/null
@@ -1,48 +0,0 @@
-package org.openapitools.client
-
-import io.kotlintest.shouldBe
-import io.kotlintest.specs.ShouldSpec
-import org.openapitools.client.apis.PetApi
-import org.openapitools.client.apis.StoreApi
-import org.openapitools.client.models.Order
-import org.openapitools.client.models.Pet
-import java.time.OffsetDateTime.now
-
-class StoreApiTest : ShouldSpec() {
-    init {
-
-        val petId:Long = 10006
-        val petApi = PetApi()
-        val storeApi = StoreApi()
-
-        val pet = Pet(
-                id = petId,
-                name = "kotlin client test",
-                photoUrls = listOf("http://test_kotlin_unit_test.com")
-        )
-        petApi.addPet(pet)
-
-        should("add an order") {
-
-            val order = Order(
-                    id = 12,
-                    petId = petId,
-                    quantity = 2,
-                    shipDate = now(),
-                    complete = true
-            )
-            storeApi.placeOrder(order);
-
-        }
-
-        should("get order by id") {
-            val result = storeApi.getOrderById(12)
-
-            // verify order
-            result.petId shouldBe (petId)
-            result.quantity shouldBe (2)
-        }
-
-    }
-
-}