fix for unboxed cases

Author: k163377

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinAnnotationIntrospector.kt

@@ -7,6 +7,7 @@ import com.fasterxml.jackson.databind.Module
 import com.fasterxml.jackson.databind.cfg.MapperConfig
 import com.fasterxml.jackson.databind.introspect.*
 import com.fasterxml.jackson.databind.jsontype.NamedType
+import com.fasterxml.jackson.databind.ser.std.StdSerializer
 import java.lang.reflect.AccessibleObject
 import java.lang.reflect.Constructor
 import java.lang.reflect.Field
@@ -62,7 +63,7 @@ internal class KotlinAnnotationIntrospector(private val context: Module.SetupCon
     }
 
     // Find a serializer to handle the case where the getter returns an unboxed value from the value class.
-    override fun findSerializer(am: Annotated): ValueClassBoxSerializer<*>? = when (am) {
+    override fun findSerializer(am: Annotated): StdSerializer<*>? = when (am) {
         is AnnotatedMethod -> {
             val getter = am.member.apply {
                 // If the return value of the getter is a value class,
@@ -87,8 +88,10 @@ internal class KotlinAnnotationIntrospector(private val context: Module.SetupCon
                 ?.takeIf { it.isValue }
                 ?.java
                 ?.let { outerClazz ->
-                    @Suppress("UNCHECKED_CAST")
-                    ValueClassBoxSerializer(outerClazz, getter.returnType)
+                    val innerClazz = getter.returnType
+
+                    ValueClassStaticJsonValueSerializer.createdOrNull(outerClazz, innerClazz)
+                        ?: @Suppress("UNCHECKED_CAST") ValueClassBoxSerializer(outerClazz, innerClazz)
                 }
         }
         // Ignore the case of AnnotatedField, because JvmField cannot be set in the field of value class.

src/main/kotlin/com/fasterxml/jackson/module/kotlin/KotlinSerializers.kt

@@ -1,5 +1,6 @@
 package com.fasterxml.jackson.module.kotlin
 
+import com.fasterxml.jackson.annotation.JsonValue
 import com.fasterxml.jackson.core.JsonGenerator
 import com.fasterxml.jackson.databind.BeanDescription
 import com.fasterxml.jackson.databind.JavaType
@@ -8,8 +9,9 @@ import com.fasterxml.jackson.databind.SerializationConfig
 import com.fasterxml.jackson.databind.SerializerProvider
 import com.fasterxml.jackson.databind.ser.Serializers
 import com.fasterxml.jackson.databind.ser.std.StdSerializer
+import java.lang.reflect.Method
+import java.lang.reflect.Modifier
 import java.math.BigInteger
-import kotlin.reflect.KClass
 
 object SequenceSerializer : StdSerializer<Sequence<*>>(Sequence::class.java) {
     override fun serialize(value: Sequence<*>, gen: JsonGenerator, provider: SerializerProvider) {
@@ -43,6 +45,10 @@ object ULongSerializer : StdSerializer<ULong>(ULong::class.java) {
     }
 }
 
+// Class must be UnboxableValueClass.
+private fun Class<*>.getStaticJsonValueGetter(): Method? = this.declaredMethods
+    .find { method -> Modifier.isStatic(method.modifiers) && method.annotations.any { it is JsonValue } }
+
 object ValueClassUnboxSerializer : StdSerializer<Any>(Any::class.java) {
     override fun serialize(value: Any, gen: JsonGenerator, provider: SerializerProvider) {
         val unboxed = value::class.java.getMethod("unbox-impl").invoke(value)
@@ -89,3 +95,27 @@ internal class ValueClassBoxSerializer<T : Any>(
         provider.findValueSerializer(outerClazz).serialize(boxed, gen, provider)
     }
 }
+
+internal class ValueClassStaticJsonValueSerializer<T> private constructor(
+    innerClazz: Class<T>,
+    private val staticJsonValueGetter: Method
+) : StdSerializer<T>(innerClazz) {
+    override fun serialize(value: T?, gen: JsonGenerator, provider: SerializerProvider) {
+        // As shown in the processing of the factory function, jsonValueGetter is always a static method.
+        val jsonValue: Any? = staticJsonValueGetter.invoke(null, value)
+        jsonValue
+            ?.let { provider.findValueSerializer(it::class.java).serialize(it, gen, provider) }
+            ?: provider.findNullValueSerializer(null).serialize(null, gen, provider)
+    }
+
+    // Since JsonValue can be processed correctly if it is given to a non-static getter/field,
+    // this class will only process if it is a `static` method.
+    companion object {
+        fun <T> createdOrNull(
+            outerClazz: Class<out Any>,
+            innerClazz: Class<T>
+        ): ValueClassStaticJsonValueSerializer<T>? = outerClazz
+            .getStaticJsonValueGetter()
+            ?.let { ValueClassStaticJsonValueSerializer(innerClazz, it) }
+    }
+}