diff --git a/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache b/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
index 174a9a0064d..2203cc43150 100644
--- a/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
+++ b/modules/openapi-generator/src/main/resources/Javascript/partial_model_generic.mustache
@@ -80,7 +80,7 @@ class {{classname}} {{#parent}}{{^parentModel}}{{#vendorExtensions.x-is-array}}e
         }
         // validate the required field `{{{baseName}}}` (array)
         for (const item of data['{{{baseName}}}']) {
-            {{{items.dataType}}}.validateJsonObject(item);
+            {{{items.dataType}}}.validateJSON(item);
         };
         {{/isRequired}}
         {{^isRequired}}
@@ -91,7 +91,7 @@ class {{classname}} {{#parent}}{{^parentModel}}{{#vendorExtensions.x-is-array}}e
             }
             // validate the optional field `{{{baseName}}}` (array)
             for (const item of data['{{{baseName}}}']) {
-                {{{items.dataType}}}.validateJsonObject(item);
+                {{{items.dataType}}}.validateJSON(item);
             };
         }
         {{/isRequired}}
diff --git a/samples/client/petstore/javascript-apollo/src/model/FileSchemaTestClass.js b/samples/client/petstore/javascript-apollo/src/model/FileSchemaTestClass.js
index 8174d56245f..1b343c6835b 100644
--- a/samples/client/petstore/javascript-apollo/src/model/FileSchemaTestClass.js
+++ b/samples/client/petstore/javascript-apollo/src/model/FileSchemaTestClass.js
@@ -74,7 +74,7 @@ class FileSchemaTestClass {
             }
             // validate the optional field `files` (array)
             for (const item of data['files']) {
-                File.validateJsonObject(item);
+                File.validateJSON(item);
             };
         }
 
diff --git a/samples/client/petstore/javascript-apollo/src/model/Pet.js b/samples/client/petstore/javascript-apollo/src/model/Pet.js
index cc5239c6a17..f1236e6dd26 100644
--- a/samples/client/petstore/javascript-apollo/src/model/Pet.js
+++ b/samples/client/petstore/javascript-apollo/src/model/Pet.js
@@ -106,7 +106,7 @@ class Pet {
             }
             // validate the optional field `tags` (array)
             for (const item of data['tags']) {
-                Tag.validateJsonObject(item);
+                Tag.validateJSON(item);
             };
         }
         // ensure the json data is a string
diff --git a/samples/client/petstore/javascript-es6/src/model/FileSchemaTestClass.js b/samples/client/petstore/javascript-es6/src/model/FileSchemaTestClass.js
index 8174d56245f..1b343c6835b 100644
--- a/samples/client/petstore/javascript-es6/src/model/FileSchemaTestClass.js
+++ b/samples/client/petstore/javascript-es6/src/model/FileSchemaTestClass.js
@@ -74,7 +74,7 @@ class FileSchemaTestClass {
             }
             // validate the optional field `files` (array)
             for (const item of data['files']) {
-                File.validateJsonObject(item);
+                File.validateJSON(item);
             };
         }
 
diff --git a/samples/client/petstore/javascript-es6/src/model/Pet.js b/samples/client/petstore/javascript-es6/src/model/Pet.js
index cc5239c6a17..f1236e6dd26 100644
--- a/samples/client/petstore/javascript-es6/src/model/Pet.js
+++ b/samples/client/petstore/javascript-es6/src/model/Pet.js
@@ -106,7 +106,7 @@ class Pet {
             }
             // validate the optional field `tags` (array)
             for (const item of data['tags']) {
-                Tag.validateJsonObject(item);
+                Tag.validateJSON(item);
             };
         }
         // ensure the json data is a string
diff --git a/samples/client/petstore/javascript-promise-es6/src/model/FileSchemaTestClass.js b/samples/client/petstore/javascript-promise-es6/src/model/FileSchemaTestClass.js
index 8174d56245f..1b343c6835b 100644
--- a/samples/client/petstore/javascript-promise-es6/src/model/FileSchemaTestClass.js
+++ b/samples/client/petstore/javascript-promise-es6/src/model/FileSchemaTestClass.js
@@ -74,7 +74,7 @@ class FileSchemaTestClass {
             }
             // validate the optional field `files` (array)
             for (const item of data['files']) {
-                File.validateJsonObject(item);
+                File.validateJSON(item);
             };
         }
 
diff --git a/samples/client/petstore/javascript-promise-es6/src/model/Pet.js b/samples/client/petstore/javascript-promise-es6/src/model/Pet.js
index cc5239c6a17..f1236e6dd26 100644
--- a/samples/client/petstore/javascript-promise-es6/src/model/Pet.js
+++ b/samples/client/petstore/javascript-promise-es6/src/model/Pet.js
@@ -106,7 +106,7 @@ class Pet {
             }
             // validate the optional field `tags` (array)
             for (const item of data['tags']) {
-                Tag.validateJsonObject(item);
+                Tag.validateJSON(item);
             };
         }
         // ensure the json data is a string
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/AdditionalPropertiesClass.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/AdditionalPropertiesClass.java
index 40e0c01aed6..d50897ade06 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/AdditionalPropertiesClass.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/AdditionalPropertiesClass.java
@@ -22,14 +22,14 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @JsonTypeName("AdditionalPropertiesClass")
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class AdditionalPropertiesClass  implements Serializable {
-  private @Valid Map<String, String> mapString = null;
-  private @Valid Map<String, BigDecimal> mapNumber = null;
-  private @Valid Map<String, Integer> mapInteger = null;
-  private @Valid Map<String, Boolean> mapBoolean = null;
-  private @Valid Map<String, List<Integer>> mapArrayInteger = null;
-  private @Valid Map<String, List<Object>> mapArrayAnytype = null;
-  private @Valid Map<String, Map<String, String>> mapMapString = null;
-  private @Valid Map<String, Map<String, Object>> mapMapAnytype = null;
+  private @Valid Map<String, String> mapString = new HashMap<>();
+  private @Valid Map<String, BigDecimal> mapNumber = new HashMap<>();
+  private @Valid Map<String, Integer> mapInteger = new HashMap<>();
+  private @Valid Map<String, Boolean> mapBoolean = new HashMap<>();
+  private @Valid Map<String, List<Integer>> mapArrayInteger = new HashMap<>();
+  private @Valid Map<String, List<Object>> mapArrayAnytype = new HashMap<>();
+  private @Valid Map<String, Map<String, String>> mapMapString = new HashMap<>();
+  private @Valid Map<String, Map<String, Object>> mapMapAnytype = new HashMap<>();
   private @Valid Object anytype1;
   private @Valid Object anytype2;
   private @Valid Object anytype3;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfArrayOfNumberOnly.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfArrayOfNumberOnly.java
index 65e80c567bc..d3f4815dfd4 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfArrayOfNumberOnly.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfArrayOfNumberOnly.java
@@ -21,7 +21,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @JsonTypeName("ArrayOfArrayOfNumberOnly")
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class ArrayOfArrayOfNumberOnly  implements Serializable {
-  private @Valid List<List<BigDecimal>> arrayArrayNumber = null;
+  private @Valid List<List<BigDecimal>> arrayArrayNumber = new ArrayList<>();
 
   protected ArrayOfArrayOfNumberOnly(ArrayOfArrayOfNumberOnlyBuilder<?, ?> b) {
     this.arrayArrayNumber = b.arrayArrayNumber;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfNumberOnly.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfNumberOnly.java
index e74a6617845..5d1799d12cb 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfNumberOnly.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayOfNumberOnly.java
@@ -21,7 +21,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @JsonTypeName("ArrayOfNumberOnly")
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class ArrayOfNumberOnly  implements Serializable {
-  private @Valid List<BigDecimal> arrayNumber = null;
+  private @Valid List<BigDecimal> arrayNumber = new ArrayList<>();
 
   protected ArrayOfNumberOnly(ArrayOfNumberOnlyBuilder<?, ?> b) {
     this.arrayNumber = b.arrayNumber;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayTest.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayTest.java
index 70c1ab60258..a40e73fdd5e 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayTest.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/ArrayTest.java
@@ -21,9 +21,9 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @JsonTypeName("ArrayTest")
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class ArrayTest  implements Serializable {
-  private @Valid List<String> arrayOfString = null;
-  private @Valid List<List<Long>> arrayArrayOfInteger = null;
-  private @Valid List<List<ReadOnlyFirst>> arrayArrayOfModel = null;
+  private @Valid List<String> arrayOfString = new ArrayList<>();
+  private @Valid List<List<Long>> arrayArrayOfInteger = new ArrayList<>();
+  private @Valid List<List<ReadOnlyFirst>> arrayArrayOfModel = new ArrayList<>();
 
   protected ArrayTest(ArrayTestBuilder<?, ?> b) {
     this.arrayOfString = b.arrayOfString;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/EnumArrays.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/EnumArrays.java
index 03069627494..4bc6f6c1b8d 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/EnumArrays.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/EnumArrays.java
@@ -115,7 +115,7 @@ public class EnumArrays  implements Serializable {
     }
 }
 
-  private @Valid List<ArrayEnumEnum> arrayEnum = null;
+  private @Valid List<ArrayEnumEnum> arrayEnum = new ArrayList<>();
 
   protected EnumArrays(EnumArraysBuilder<?, ?> b) {
     this.justSymbol = b.justSymbol;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/FileSchemaTestClass.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/FileSchemaTestClass.java
index 14d58e3e3d5..60a19b11f1b 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/FileSchemaTestClass.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/FileSchemaTestClass.java
@@ -22,7 +22,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class FileSchemaTestClass  implements Serializable {
   private @Valid ModelFile _file;
-  private @Valid List<ModelFile> files = null;
+  private @Valid List<ModelFile> files = new ArrayList<>();
 
   protected FileSchemaTestClass(FileSchemaTestClassBuilder<?, ?> b) {
     this._file = b._file;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MapTest.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MapTest.java
index 9eb62b626f2..96271afa1ce 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MapTest.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MapTest.java
@@ -20,7 +20,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 @JsonTypeName("MapTest")
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaJAXRSSpecServerCodegen")
 public class MapTest  implements Serializable {
-  private @Valid Map<String, Map<String, String>> mapMapOfString = null;
+  private @Valid Map<String, Map<String, String>> mapMapOfString = new HashMap<>();
   public enum InnerEnum {
 
     UPPER(String.valueOf("UPPER")), LOWER(String.valueOf("lower"));
@@ -68,9 +68,9 @@ public class MapTest  implements Serializable {
     }
 }
 
-  private @Valid Map<String, InnerEnum> mapOfEnumString = null;
-  private @Valid Map<String, Boolean> directMap = null;
-  private @Valid Map<String, Boolean> indirectMap = null;
+  private @Valid Map<String, InnerEnum> mapOfEnumString = new HashMap<>();
+  private @Valid Map<String, Boolean> directMap = new HashMap<>();
+  private @Valid Map<String, Boolean> indirectMap = new HashMap<>();
 
   protected MapTest(MapTestBuilder<?, ?> b) {
     this.mapMapOfString = b.mapMapOfString;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MixedPropertiesAndAdditionalPropertiesClass.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MixedPropertiesAndAdditionalPropertiesClass.java
index 7d72e6ba39f..6e5d8d9d466 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MixedPropertiesAndAdditionalPropertiesClass.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/MixedPropertiesAndAdditionalPropertiesClass.java
@@ -25,7 +25,7 @@ import com.fasterxml.jackson.annotation.JsonTypeName;
 public class MixedPropertiesAndAdditionalPropertiesClass  implements Serializable {
   private @Valid UUID uuid;
   private @Valid Date dateTime;
-  private @Valid Map<String, Animal> map = null;
+  private @Valid Map<String, Animal> map = new HashMap<>();
 
   protected MixedPropertiesAndAdditionalPropertiesClass(MixedPropertiesAndAdditionalPropertiesClassBuilder<?, ?> b) {
     this.uuid = b.uuid;
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/Pet.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/Pet.java
index c273059826c..724992ffb63 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/Pet.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/Pet.java
@@ -29,7 +29,7 @@ public class Pet  implements Serializable {
   private @Valid Category category;
   private @Valid String name;
   private @Valid Set<String> photoUrls = new LinkedHashSet<>();
-  private @Valid List<Tag> tags = null;
+  private @Valid List<Tag> tags = new ArrayList<>();
   public enum StatusEnum {
 
     AVAILABLE(String.valueOf("available")), PENDING(String.valueOf("pending")), SOLD(String.valueOf("sold"));
diff --git a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/XmlItem.java b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/XmlItem.java
index d119b26c375..cfc0fd1baba 100644
--- a/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/XmlItem.java
+++ b/samples/server/petstore/jaxrs-spec-jakarta/src/gen/java/org/openapitools/model/XmlItem.java
@@ -25,31 +25,31 @@ public class XmlItem  implements Serializable {
   private @Valid BigDecimal attributeNumber;
   private @Valid Integer attributeInteger;
   private @Valid Boolean attributeBoolean;
-  private @Valid List<Integer> wrappedArray = null;
+  private @Valid List<Integer> wrappedArray = new ArrayList<>();
   private @Valid String nameString;
   private @Valid BigDecimal nameNumber;
   private @Valid Integer nameInteger;
   private @Valid Boolean nameBoolean;
-  private @Valid List<Integer> nameArray = null;
-  private @Valid List<Integer> nameWrappedArray = null;
+  private @Valid List<Integer> nameArray = new ArrayList<>();
+  private @Valid List<Integer> nameWrappedArray = new ArrayList<>();
   private @Valid String prefixString;
   private @Valid BigDecimal prefixNumber;
   private @Valid Integer prefixInteger;
   private @Valid Boolean prefixBoolean;
-  private @Valid List<Integer> prefixArray = null;
-  private @Valid List<Integer> prefixWrappedArray = null;
+  private @Valid List<Integer> prefixArray = new ArrayList<>();
+  private @Valid List<Integer> prefixWrappedArray = new ArrayList<>();
   private @Valid String namespaceString;
   private @Valid BigDecimal namespaceNumber;
   private @Valid Integer namespaceInteger;
   private @Valid Boolean namespaceBoolean;
-  private @Valid List<Integer> namespaceArray = null;
-  private @Valid List<Integer> namespaceWrappedArray = null;
+  private @Valid List<Integer> namespaceArray = new ArrayList<>();
+  private @Valid List<Integer> namespaceWrappedArray = new ArrayList<>();
   private @Valid String prefixNsString;
   private @Valid BigDecimal prefixNsNumber;
   private @Valid Integer prefixNsInteger;
   private @Valid Boolean prefixNsBoolean;
-  private @Valid List<Integer> prefixNsArray = null;
-  private @Valid List<Integer> prefixNsWrappedArray = null;
+  private @Valid List<Integer> prefixNsArray = new ArrayList<>();
+  private @Valid List<Integer> prefixNsWrappedArray = new ArrayList<>();
 
   protected XmlItem(XmlItemBuilder<?, ?> b) {
     this.attributeString = b.attributeString;