diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
index 7ab48af34a9..aaf5489eb6d 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
@@ -1297,6 +1297,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
         }
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     public Map<String, Object> postProcessModels(Map<String, Object> objs) {
         // recursively add import for mapping one type to multiple imports
@@ -1316,6 +1317,18 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
             }
         }
 
+        List<Object> models = (List<Object>) objs.get("models");
+
+        for (Object _mo : models) {
+            Map<String, Object> mo = (Map<String, Object>) _mo;
+            CodegenModel cm = (CodegenModel) mo.get("model");
+
+            cm.getVendorExtensions().putIfAbsent("x-implements", new ArrayList<String>());
+            if (this.serializableModel) {
+                ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Serializable");
+            }
+        }
+
         return postProcessModelsEnum(objs);
     }
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
index faefb758d5f..330744bca40 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
@@ -904,9 +904,6 @@ public class JavaClientCodegen extends AbstractJavaCodegen
             if (this.parcelableModel) {
                 ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Parcelable");
             }
-            if (this.serializableModel) {
-                ((ArrayList<String>) cm.getVendorExtensions().get("x-implements")).add("Serializable");
-            }
         }
 
         return objs;
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache
index f2f269ab7cb..a2495063334 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/microprofile/pojo.mustache
@@ -37,7 +37,7 @@ import javax.json.bind.annotation.JsonbCreator;
  **/
 {{/description}}
 {{>additionalModelTypeAnnotations}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#serializableModel}} implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#vendorExtensions.x-implements}}{{#-first}} implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
 {{>enumClass}}{{/mostInnerItems}}{{/isContainer}}{{/isEnum}}
diff --git a/modules/openapi-generator/src/main/resources/JavaInflector/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaInflector/pojo.mustache
index 408a4a759b3..fa64a4974e0 100644
--- a/modules/openapi-generator/src/main/resources/JavaInflector/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaInflector/pojo.mustache
@@ -1,6 +1,6 @@
 {{#description}}@ApiModel(description = "{{{.}}}"){{/description}}
 {{>generatedAnnotation}}{{>additionalModelTypeAnnotations}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}
     {{#isEnum}}
     {{^isContainer}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-cdi/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-cdi/pojo.mustache
index 34aa341352a..a71c6f8aa64 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-cdi/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-cdi/pojo.mustache
@@ -6,7 +6,7 @@ import javax.xml.bind.annotation.*;
 {{/withXml}}
 
 {{#description}}@ApiModel(description = "{{{.}}}"){{/description}}{{>additionalModelTypeAnnotations}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-ext/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-ext/pojo.mustache
index 226ef4c69a5..266a3e1b4a6 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-ext/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf-ext/pojo.mustache
@@ -25,7 +25,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
  */
 @ApiModel(description="{{{description}}}")
 {{/description}}{{>additionalModelTypeAnnotations}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#serializableModel}} implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#vendorExtensions.x-implements}}{{#-first}} implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
 {{>enumClass}}{{/mostInnerItems}}{{/isContainer}}{{/isEnum}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf/pojo.mustache
index aab11b08675..c1de5d81811 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/cxf/pojo.mustache
@@ -16,7 +16,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
  **/
 @ApiModel(description="{{{description}}}")
 {{/description}}
-{{>additionalModelTypeAnnotations}}{{>xmlPojoAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#serializableModel}} implements Serializable{{/serializableModel}} {
+{{>additionalModelTypeAnnotations}}{{>xmlPojoAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{#vendorExtensions.x-implements}}{{#-first}} implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
 {{>enumClass}}{{/mostInnerItems}}{{/isContainer}}{{/isEnum}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/pojo.mustache
index dd695a52ae3..3ea8689b1ef 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/pojo.mustache
@@ -10,7 +10,7 @@
 })
 {{/jackson}}
 {{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}
     {{#isEnum}}
     {{^isContainer}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/pojo.mustache
index 8bbfc430101..bd4124fe76c 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/eap/pojo.mustache
@@ -1,7 +1,7 @@
 import io.swagger.annotations.*;
 
 {{#description}}@ApiModel(description="{{{.}}}"){{/description}}{{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
 {{#serializableModel}}
   private static final long serialVersionUID = 1L;
 {{/serializableModel}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/pojo.mustache
index 50b1c726407..15f8f721393 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/resteasy/pojo.mustache
@@ -1,7 +1,7 @@
 import io.swagger.annotations.*;
 
 {{#description}}@ApiModel(description="{{{.}}}"){{/description}}{{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
 {{#serializableModel}}
   private static final long serialVersionUID = 1L;
 {{/serializableModel}}
diff --git a/modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache
index 62f1137a488..7b2005333ee 100644
--- a/modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache
@@ -12,7 +12,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
  **/{{/description}}
 {{#useSwaggerAnnotations}}{{#description}}@ApiModel(description = "{{{.}}}"){{/description}}{{/useSwaggerAnnotations}}
 @JsonTypeName("{{name}}")
-{{>generatedAnnotation}}{{>additionalModelTypeAnnotations}}public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+{{>generatedAnnotation}}{{>additionalModelTypeAnnotations}}public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
diff --git a/modules/openapi-generator/src/main/resources/JavaPlayFramework/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaPlayFramework/pojo.mustache
index f99576d8383..d31c1843882 100644
--- a/modules/openapi-generator/src/main/resources/JavaPlayFramework/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaPlayFramework/pojo.mustache
@@ -7,7 +7,7 @@ import javax.validation.constraints.*;
  */
 {{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}
 @SuppressWarnings({"UnusedReturnValue", "WeakerAccess"})
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}
     {{#isEnum}}
     {{^isContainer}}
diff --git a/modules/openapi-generator/src/main/resources/JavaSpring/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaSpring/pojo.mustache
index 9478514e3e1..21e63a388fb 100644
--- a/modules/openapi-generator/src/main/resources/JavaSpring/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaSpring/pojo.mustache
@@ -22,7 +22,7 @@
 {{>xmlAnnotation}}
 {{/withXml}}
 {{>generatedAnnotation}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{^parent}}{{#hateoas}}extends RepresentationModel<{{classname}}> {{/hateoas}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}}{{^parent}}{{#hateoas}}extends RepresentationModel<{{classname}}> {{/hateoas}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
 {{#serializableModel}}
 
   private static final long serialVersionUID = 1L;
diff --git a/modules/openapi-generator/src/main/resources/JavaVertXServer/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaVertXServer/pojo.mustache
index f5ac4490774..2b2dd7c5ff0 100644
--- a/modules/openapi-generator/src/main/resources/JavaVertXServer/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaVertXServer/pojo.mustache
@@ -1,5 +1,5 @@
 {{>additionalModelTypeAnnotations}}@JsonInclude(JsonInclude.Include.NON_NULL)
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
diff --git a/modules/openapi-generator/src/main/resources/JavaVertXWebServer/pojo.mustache b/modules/openapi-generator/src/main/resources/JavaVertXWebServer/pojo.mustache
index f5ac4490774..2b2dd7c5ff0 100644
--- a/modules/openapi-generator/src/main/resources/JavaVertXWebServer/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/JavaVertXWebServer/pojo.mustache
@@ -1,5 +1,5 @@
 {{>additionalModelTypeAnnotations}}@JsonInclude(JsonInclude.Include.NON_NULL)
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}
diff --git a/modules/openapi-generator/src/main/resources/java-msf4j-server/pojo.mustache b/modules/openapi-generator/src/main/resources/java-msf4j-server/pojo.mustache
index 790e8635b50..743698ea9f5 100644
--- a/modules/openapi-generator/src/main/resources/java-msf4j-server/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/java-msf4j-server/pojo.mustache
@@ -3,7 +3,7 @@
  */{{#description}}
 @ApiModel(description = "{{{.}}}"){{/description}}
 {{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}
     {{#isEnum}}
     {{^isContainer}}
diff --git a/modules/openapi-generator/src/main/resources/java-pkmst/pojo.mustache b/modules/openapi-generator/src/main/resources/java-pkmst/pojo.mustache
index 31d7d300274..6609c81a3ce 100644
--- a/modules/openapi-generator/src/main/resources/java-pkmst/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/java-pkmst/pojo.mustache
@@ -4,7 +4,7 @@
 @ApiModel(description = "{{{.}}}"){{/description}}
 {{#useBeanValidation}}@Validated{{/useBeanValidation}}
 {{>generatedAnnotation}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{>xmlAnnotation}}{{>additionalModelTypeAnnotations}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
 {{#serializableModel}}
   private static final long serialVersionUID = 1L;
 
diff --git a/modules/openapi-generator/src/main/resources/java-undertow-server/pojo.mustache b/modules/openapi-generator/src/main/resources/java-undertow-server/pojo.mustache
index 95e66a258da..9f8e2086821 100644
--- a/modules/openapi-generator/src/main/resources/java-undertow-server/pojo.mustache
+++ b/modules/openapi-generator/src/main/resources/java-undertow-server/pojo.mustache
@@ -1,6 +1,6 @@
 {{#description}}@ApiModel(description = "{{{.}}}"){{/description}}
 {{>additionalModelTypeAnnotations}}{{>generatedAnnotation}}
-public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#serializableModel}}implements Serializable{{/serializableModel}} {
+public class {{classname}} {{#parent}}extends {{{.}}}{{/parent}} {{#vendorExtensions.x-implements}}{{#-first}}implements {{{.}}}{{/-first}}{{^-first}}, {{{.}}}{{/-first}}{{/vendorExtensions.x-implements}} {
   {{#vars}}{{#isEnum}}{{^isContainer}}
 
 {{>enumClass}}{{/isContainer}}{{#isContainer}}{{#mostInnerItems}}