diff --git a/modules/swagger-codegen/src/main/resources/Java/api.mustache b/modules/swagger-codegen/src/main/resources/Java/api.mustache
index a1c9e05042..78bac41d9d 100644
--- a/modules/swagger-codegen/src/main/resources/Java/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/api.mustache
@@ -45,12 +45,12 @@ public class {{classname}} {
    */
   public {{#returnType}}{{{returnType}}} {{/returnType}}{{^returnType}}void {{/returnType}}{{nickname}} ({{#allParams}}{{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) throws ApiException {
     Object postBody = {{#bodyParam}}{{paramName}}{{/bodyParam}}{{^bodyParam}}null{{/bodyParam}};
-    {{#requiredParamCount}}
-    // verify required params are set
-    if({{/requiredParamCount}}{{#requiredParams}} {{paramName}} == null {{#hasMore}}|| {{/hasMore}}{{/requiredParams}}{{#requiredParamCount}}) {
-       throw new ApiException(400, "missing required params");
+    {{#allParams}}{{#required}}
+    // verify the required parameter '{{paramName}}' is set
+    if ({{paramName}} == null) {
+       throw new ApiException(400, "Missing the required parameter '{{paramName}}' when calling {{nickname}}");
     }
-    {{/requiredParamCount}}
+    {{/required}}{{/allParams}}
 
     // create path and map variables
     String path = "{{path}}".replaceAll("\\{format\\}","json"){{#pathParams}}
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/src/main/java/io/swagger/client/api/PetApi.java
index 842c080024..b5d6bb70d7 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/api/PetApi.java
@@ -249,6 +249,11 @@ public class PetApi {
   public Pet getPetById (Long petId) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'petId' is set
+    if (petId == null) {
+       throw new ApiException(400, "Missing the required parameter 'petId' when calling getPetById");
+    }
+    
 
     // create path and map variables
     String path = "/pet/{petId}".replaceAll("\\{format\\}","json")
@@ -302,6 +307,11 @@ public class PetApi {
   public void updatePetWithForm (String petId, String name, String status) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'petId' is set
+    if (petId == null) {
+       throw new ApiException(400, "Missing the required parameter 'petId' when calling updatePetWithForm");
+    }
+    
 
     // create path and map variables
     String path = "/pet/{petId}".replaceAll("\\{format\\}","json")
@@ -362,6 +372,11 @@ public class PetApi {
   public void deletePet (String apiKey, Long petId) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'petId' is set
+    if (petId == null) {
+       throw new ApiException(400, "Missing the required parameter 'petId' when calling deletePet");
+    }
+    
 
     // create path and map variables
     String path = "/pet/{petId}".replaceAll("\\{format\\}","json")
@@ -416,6 +431,11 @@ public class PetApi {
   public void uploadFile (Long petId, String additionalMetadata, File file) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'petId' is set
+    if (petId == null) {
+       throw new ApiException(400, "Missing the required parameter 'petId' when calling uploadFile");
+    }
+    
 
     // create path and map variables
     String path = "/pet/{petId}/uploadImage".replaceAll("\\{format\\}","json")
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/src/main/java/io/swagger/client/api/StoreApi.java
index cff340e69d..6da7b5abb2 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/api/StoreApi.java
@@ -144,6 +144,11 @@ public class StoreApi {
   public Order getOrderById (String orderId) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'orderId' is set
+    if (orderId == null) {
+       throw new ApiException(400, "Missing the required parameter 'orderId' when calling getOrderById");
+    }
+    
 
     // create path and map variables
     String path = "/store/order/{orderId}".replaceAll("\\{format\\}","json")
@@ -195,6 +200,11 @@ public class StoreApi {
   public void deleteOrder (String orderId) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'orderId' is set
+    if (orderId == null) {
+       throw new ApiException(400, "Missing the required parameter 'orderId' when calling deleteOrder");
+    }
+    
 
     // create path and map variables
     String path = "/store/order/{orderId}".replaceAll("\\{format\\}","json")
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/src/main/java/io/swagger/client/api/UserApi.java
index 2296c0223c..d0974d95a5 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/api/UserApi.java
@@ -299,6 +299,11 @@ public class UserApi {
   public User getUserByName (String username) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'username' is set
+    if (username == null) {
+       throw new ApiException(400, "Missing the required parameter 'username' when calling getUserByName");
+    }
+    
 
     // create path and map variables
     String path = "/user/{username}".replaceAll("\\{format\\}","json")
@@ -351,6 +356,11 @@ public class UserApi {
   public void updateUser (String username, User body) throws ApiException {
     Object postBody = body;
     
+    // verify the required parameter 'username' is set
+    if (username == null) {
+       throw new ApiException(400, "Missing the required parameter 'username' when calling updateUser");
+    }
+    
 
     // create path and map variables
     String path = "/user/{username}".replaceAll("\\{format\\}","json")
@@ -402,6 +412,11 @@ public class UserApi {
   public void deleteUser (String username) throws ApiException {
     Object postBody = null;
     
+    // verify the required parameter 'username' is set
+    if (username == null) {
+       throw new ApiException(400, "Missing the required parameter 'username' when calling deleteUser");
+    }
+    
 
     // create path and map variables
     String path = "/user/{username}".replaceAll("\\{format\\}","json")