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 a605c94c8bfce50a4b6d0061ee9e6b9e4734cd35..9c3a2930478ce8cfde744c2bcc7e89c6f68b460f 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
@@ -957,8 +957,6 @@ public class JavaClientCodegen extends AbstractJavaCodegen
 
             cm.getVendorExtensions().putIfAbsent("x-implements", new ArrayList<String>());
             if (JERSEY2.equals(getLibrary()) || JERSEY3.equals(getLibrary()) || NATIVE.equals(getLibrary()) || OKHTTP_GSON.equals(getLibrary())) {
-                cm.getVendorExtensions().put("x-implements", new ArrayList<String>());
-
                 if (cm.oneOf != null && !cm.oneOf.isEmpty() && cm.oneOf.contains("ModelNull")) {
                     // if oneOf contains "null" type
                     cm.isNullable = true;