diff --git a/modules/swagger-codegen/src/main/resources/Java/JSON.mustache b/modules/swagger-codegen/src/main/resources/Java/JSON.mustache
index 7689856f5de..43b38f6e21d 100644
--- a/modules/swagger-codegen/src/main/resources/Java/JSON.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/JSON.mustache
@@ -12,12 +12,13 @@ public class JSON {
 
   public JSON() {
     mapper = new ObjectMapper();
+    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
     mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
     mapper.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
     mapper.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
     mapper.registerModule(new JodaModule());
-	}
+  }
 
   /**
    * Serialize the given Java object into JSON string.
diff --git a/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache b/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache
index 10a43d97de0..9cc1324acb6 100644
--- a/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/libraries/okhttp-gson/JSON.mustache
@@ -23,10 +23,9 @@ public class JSON {
   public JSON(ApiClient apiClient) {
     this.apiClient = apiClient;
     gson = new GsonBuilder()
-      .serializeNulls()
       .registerTypeAdapter(Date.class, new DateAdapter(apiClient))
       .create();
-	}
+  }
 
   public Gson getGson() {
     return gson;
diff --git a/samples/client/petstore/java/default/src/main/java/io/swagger/client/JSON.java b/samples/client/petstore/java/default/src/main/java/io/swagger/client/JSON.java
index 3e15ec01d3b..1986a6badbf 100644
--- a/samples/client/petstore/java/default/src/main/java/io/swagger/client/JSON.java
+++ b/samples/client/petstore/java/default/src/main/java/io/swagger/client/JSON.java
@@ -6,18 +6,19 @@ import com.fasterxml.jackson.datatype.joda.*;
 
 import java.io.IOException;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T10:56:59.550-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:29.717+08:00")
 public class JSON {
   private ObjectMapper mapper;
 
   public JSON() {
     mapper = new ObjectMapper();
+    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
     mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
     mapper.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
     mapper.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
     mapper.registerModule(new JodaModule());
-	}
+  }
 
   /**
    * Serialize the given Java object into JSON string.
diff --git a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/PetApi.java
index 2c7d0be8279..23782e03e72 100644
--- a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/PetApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import io.swagger.client.model.Pet;
 import java.io.File;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T10:56:59.550-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:29.717+08:00")
 public class PetApi {
   private ApiClient apiClient;
 
@@ -272,7 +266,7 @@ public class PetApi {
     };
     final String contentType = apiClient.selectHeaderContentType(contentTypes);
 
-    String[] authNames = new String[] { "api_key", "petstore_auth" };
+    String[] authNames = new String[] { "api_key" };
 
     
 
diff --git a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/StoreApi.java
index 8cb88dfcd31..f8c0fc58682 100644
--- a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/StoreApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import java.util.Map;
 import io.swagger.client.model.Order;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T10:56:59.550-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:29.717+08:00")
 public class StoreApi {
   private ApiClient apiClient;
 
diff --git a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/UserApi.java
index 8db3eaffacc..f6ab0ae0814 100644
--- a/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/default/src/main/java/io/swagger/client/api/UserApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import io.swagger.client.model.User;
 import java.util.*;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T10:56:59.550-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:29.717+08:00")
 public class UserApi {
   private ApiClient apiClient;
 
diff --git a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/JSON.java b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/JSON.java
index 0ba2992593a..8ce930ce5c1 100644
--- a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/JSON.java
+++ b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/JSON.java
@@ -6,18 +6,19 @@ import com.fasterxml.jackson.datatype.joda.*;
 
 import java.io.IOException;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T11:29:47.599-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:20.020+08:00")
 public class JSON {
   private ObjectMapper mapper;
 
   public JSON() {
     mapper = new ObjectMapper();
+    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
     mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
     mapper.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
     mapper.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
     mapper.registerModule(new JodaModule());
-	}
+  }
 
   /**
    * Serialize the given Java object into JSON string.
diff --git a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/PetApi.java
index 698ba3dfa19..57c087a7b5f 100644
--- a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/PetApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import io.swagger.client.model.Pet;
 import java.io.File;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T11:29:47.599-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:20.020+08:00")
 public class PetApi {
   private ApiClient apiClient;
 
@@ -243,7 +237,7 @@ public class PetApi {
     };
     final String contentType = apiClient.selectHeaderContentType(contentTypes);
 
-    String[] authNames = new String[] { "api_key", "petstore_auth" };
+    String[] authNames = new String[] { "api_key" };
 
     
     TypeRef returnType = new TypeRef<Pet>() {};
diff --git a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/StoreApi.java
index b2392910993..b035cde9658 100644
--- a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/StoreApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import java.util.Map;
 import io.swagger.client.model.Order;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T11:29:47.599-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:20.020+08:00")
 public class StoreApi {
   private ApiClient apiClient;
 
diff --git a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/UserApi.java
index b5ef542f876..51bac269b53 100644
--- a/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/jersey2/src/main/java/io/swagger/client/api/UserApi.java
@@ -6,18 +6,12 @@ import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 import io.swagger.client.TypeRef;
 
-import io.swagger.client.model.*;
-
-import java.util.*;
-
 import io.swagger.client.model.User;
 import java.util.*;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.util.*;
 
-@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-20T11:29:47.599-07:00")
+@javax.annotation.Generated(value = "class io.swagger.codegen.languages.JavaClientCodegen", date = "2015-10-21T11:55:20.020+08:00")
 public class UserApi {
   private ApiClient apiClient;
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/JSON.java b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/JSON.java
index f88639b9c82..d9d0881a153 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/JSON.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/JSON.java
@@ -23,10 +23,9 @@ public class JSON {
   public JSON(ApiClient apiClient) {
     this.apiClient = apiClient;
     gson = new GsonBuilder()
-      .serializeNulls()
       .registerTypeAdapter(Date.class, new DateAdapter(apiClient))
       .create();
-	}
+  }
 
   public Gson getGson() {
     return gson;
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/PetApi.java
index ff6a1e9b558..39154cf855e 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/PetApi.java
@@ -6,22 +6,15 @@ import io.swagger.client.ApiException;
 import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 
-import io.swagger.client.model.*;
-
 import com.google.gson.reflect.TypeToken;
 
 import com.squareup.okhttp.Call;
 
-import java.lang.reflect.Type;
-
-import java.util.*;
-
 import io.swagger.client.model.Pet;
 import java.io.File;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.lang.reflect.Type;
+import java.util.*;
 
 public class PetApi {
   private ApiClient apiClient;
@@ -297,7 +290,7 @@ public class PetApi {
     final String contentType = apiClient.selectHeaderContentType(contentTypes);
     headerParams.put("Content-Type", contentType);
 
-    String[] authNames = new String[] { "api_key", "petstore_auth" };
+    String[] authNames = new String[] { "api_key" };
     return apiClient.buildCall(path, "GET", queryParams, postBody, headerParams, formParams, authNames);
   }
 
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/StoreApi.java
index a3fb14bb521..cb780538e18 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/StoreApi.java
@@ -6,22 +6,15 @@ import io.swagger.client.ApiException;
 import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 
-import io.swagger.client.model.*;
-
 import com.google.gson.reflect.TypeToken;
 
 import com.squareup.okhttp.Call;
 
-import java.lang.reflect.Type;
-
-import java.util.*;
-
 import java.util.Map;
 import io.swagger.client.model.Order;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.lang.reflect.Type;
+import java.util.*;
 
 public class StoreApi {
   private ApiClient apiClient;
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/UserApi.java
index ce1bae64a46..a04470b3b40 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/UserApi.java
@@ -6,22 +6,15 @@ import io.swagger.client.ApiException;
 import io.swagger.client.Configuration;
 import io.swagger.client.Pair;
 
-import io.swagger.client.model.*;
-
 import com.google.gson.reflect.TypeToken;
 
 import com.squareup.okhttp.Call;
 
-import java.lang.reflect.Type;
-
-import java.util.*;
-
 import io.swagger.client.model.User;
 import java.util.*;
 
-import java.io.File;
-import java.util.Map;
-import java.util.HashMap;
+import java.lang.reflect.Type;
+import java.util.*;
 
 public class UserApi {
   private ApiClient apiClient;