fix(java): plus url encoding (#15539)

Author: PYPL-Song

modules/openapi-generator/src/main/resources/Java/libraries/native/ApiClient.mustache

@@ -74,7 +74,7 @@ public class ApiClient {
    * @return URL-encoded representation of the input string.
    */
   public static String urlEncode(String s) {
-    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%20");
+    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%2B");
   }
 
   /**

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

@@ -1359,7 +1359,7 @@ public void testNativeClientWhiteSpacePathParamEncoding() throws IOException {
         validateJavaSourceFiles(files);
 
         TestUtils.assertFileContains(Paths.get(output + "/src/main/java/xyz/abcdef/ApiClient.java"),
-                "public static String urlEncode(String s) { return URLEncoder.encode(s, UTF_8).replaceAll(\"\\\\+\", \"%20\"); }");
+                "public static String urlEncode(String s) { return URLEncoder.encode(s, UTF_8).replaceAll(\"\\\\+\", \"%2B\"); }");
     }
 
     /**

samples/client/petstore/java/native-async/src/main/java/org/openapitools/client/ApiClient.java

@@ -83,7 +83,7 @@ private static String valueToString(Object value) {
    * @return URL-encoded representation of the input string.
    */
   public static String urlEncode(String s) {
-    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%20");
+    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%2B");
   }
 
   /**

samples/client/petstore/java/native/src/main/java/org/openapitools/client/ApiClient.java

@@ -83,7 +83,7 @@ private static String valueToString(Object value) {
    * @return URL-encoded representation of the input string.
    */
   public static String urlEncode(String s) {
-    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%20");
+    return URLEncoder.encode(s, UTF_8).replaceAll("\\+", "%2B");
   }
 
   /**