diff --git a/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/api/FakeApi.java b/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/api/FakeApi.java
index 100f900f644..f5df2bb813f 100644
--- a/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/api/FakeApi.java
+++ b/samples/client/petstore/java/jersey1/src/main/java/io/swagger/client/api/FakeApi.java
@@ -420,6 +420,7 @@ if (enumQueryDouble != null)
 
     // query params
     List<Pair> localVarQueryParams = new ArrayList<Pair>();
+    List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
     Map<String, String> localVarHeaderParams = new HashMap<String, String>();
     Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
@@ -443,6 +444,6 @@ if (param2 != null)
     String[] localVarAuthNames = new String[] {  };
 
 
-    apiClient.invokeAPI(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, null);
+    apiClient.invokeAPI(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, null);
   }
 }
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/ApiClient.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/ApiClient.java
index fcd280ecdec..0a2fa401474 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/ApiClient.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/ApiClient.java
@@ -466,62 +466,70 @@ public class ApiClient {
     }
 
     /**
-     * Format to {@code Pair} objects.
+     * Formats the specified query parameter to a list containing a single {@code Pair} object.
      *
-     * @param collectionFormat collection format (e.g. csv, tsv)
-     * @param name Name
-     * @param value Value
-     * @return A list of Pair objects
+     * Note that {@code value} must not be a collection.
+     *
+     * @param name The name of the parameter.
+     * @param value The value of the parameter.
+     * @return A list containing a single {@code Pair} object.
      */
-    public List<Pair> parameterToPairs(String collectionFormat, String name, Object value){
+    public List<Pair> parameterToPair(String name, Object value) {
         List<Pair> params = new ArrayList<Pair>();
 
         // preconditions
-        if (name == null || name.isEmpty() || value == null) return params;
+        if (name == null || name.isEmpty() || value == null || value instanceof Collection) return params;
 
-        Collection valueCollection = null;
-        if (value instanceof Collection) {
-            valueCollection = (Collection) value;
-        } else {
-            params.add(new Pair(name, parameterToString(value)));
+        params.add(new Pair(name, parameterToString(value)));
+        return params;
+    }
+
+    /**
+     * Formats the specified collection query parameters to a list of {@code Pair} objects.
+     *
+     * Note that the values of each of the returned Pair objects are percent-encoded.
+     *
+     * @param collectionFormat The collection format of the parameter.
+     * @param name The name of the parameter.
+     * @param value The value of the parameter.
+     * @return A list of {@code Pair} objects.
+     */
+    public List<Pair> parameterToPairs(String collectionFormat, String name, Collection value) {
+        List<Pair> params = new ArrayList<Pair>();
+
+        // preconditions
+        if (name == null || name.isEmpty() || value == null || value.isEmpty()) {
             return params;
         }
 
-        if (valueCollection.isEmpty()){
-            return params;
-        }
-
-        // get the collection format
-        collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv
-
         // create the params based on the collection format
-        if (collectionFormat.equals("multi")) {
-            for (Object item : valueCollection) {
-                params.add(new Pair(name, parameterToString(item)));
+        if ("multi".equals(collectionFormat)) {
+            for (Object item : value) {
+                params.add(new Pair(name, escapeString(parameterToString(item))));
             }
-
             return params;
         }
 
+        // collectionFormat is assumed to be "csv" by default
         String delimiter = ",";
 
-        if (collectionFormat.equals("csv")) {
-            delimiter = ",";
-        } else if (collectionFormat.equals("ssv")) {
-            delimiter = " ";
-        } else if (collectionFormat.equals("tsv")) {
-            delimiter = "\t";
-        } else if (collectionFormat.equals("pipes")) {
-            delimiter = "|";
+        // escape all delimiters except commas, which are URI reserved
+        // characters
+        if ("ssv".equals(collectionFormat)) {
+            delimiter = escapeString(" ");
+        } else if ("tsv".equals(collectionFormat)) {
+            delimiter = escapeString("\t");
+        } else if ("pipes".equals(collectionFormat)) {
+            delimiter = escapeString("|");
         }
 
         StringBuilder sb = new StringBuilder() ;
-        for (Object item : valueCollection) {
+        for (Object item : value) {
             sb.append(delimiter);
-            sb.append(parameterToString(item));
+            sb.append(escapeString(parameterToString(item)));
         }
 
-        params.add(new Pair(name, sb.substring(1)));
+        params.add(new Pair(name, sb.substring(delimiter.length())));
 
         return params;
     }
@@ -881,6 +889,7 @@ public class ApiClient {
      * @param path The sub-path of the HTTP URL
      * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
      * @param queryParams The query parameters
+     * @param collectionQueryParams The collection query parameters
      * @param body The request body object
      * @param headerParams The header parameters
      * @param formParams The form parameters
@@ -889,8 +898,8 @@ public class ApiClient {
      * @return The HTTP call
      * @throws ApiException If fail to serialize the request body object
      */
-    public Call buildCall(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
-        Request request = buildRequest(path, method, queryParams, body, headerParams, formParams, authNames, progressRequestListener);
+    public Call buildCall(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
+        Request request = buildRequest(path, method, queryParams, collectionQueryParams, body, headerParams, formParams, authNames, progressRequestListener);
 
         return httpClient.newCall(request);
     }
@@ -901,6 +910,7 @@ public class ApiClient {
      * @param path The sub-path of the HTTP URL
      * @param method The request method, one of "GET", "HEAD", "OPTIONS", "POST", "PUT", "PATCH" and "DELETE"
      * @param queryParams The query parameters
+     * @param collectionQueryParams The collection query parameters
      * @param body The request body object
      * @param headerParams The header parameters
      * @param formParams The form parameters
@@ -909,10 +919,10 @@ public class ApiClient {
      * @return The HTTP request 
      * @throws ApiException If fail to serialize the request body object
      */
-    public Request buildRequest(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
+    public Request buildRequest(String path, String method, List<Pair> queryParams, List<Pair> collectionQueryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String[] authNames, ProgressRequestBody.ProgressRequestListener progressRequestListener) throws ApiException {
         updateParamsForAuth(authNames, queryParams, headerParams);
 
-        final String url = buildUrl(path, queryParams);
+        final String url = buildUrl(path, queryParams, collectionQueryParams);
         final Request.Builder reqBuilder = new Request.Builder().url(url);
         processHeaderParams(headerParams, reqBuilder);
 
@@ -958,9 +968,10 @@ public class ApiClient {
      *
      * @param path The sub path
      * @param queryParams The query parameters
+     * @param collectionQueryParams The collection query parameters
      * @return The full URL
      */
-    public String buildUrl(String path, List<Pair> queryParams) {
+    public String buildUrl(String path, List<Pair> queryParams, List<Pair> collectionQueryParams) {
         final StringBuilder url = new StringBuilder();
         url.append(basePath).append(path);
 
@@ -981,6 +992,23 @@ public class ApiClient {
             }
         }
 
+        if (collectionQueryParams != null && !collectionQueryParams.isEmpty()) {
+            String prefix = url.toString().contains("?") ? "&" : "?";
+            for (Pair param : collectionQueryParams) {
+                if (param.getValue() != null) {
+                    if (prefix != null) {
+                        url.append(prefix);
+                        prefix = null;
+                    } else {
+                        url.append("&");
+                    }
+                    String value = parameterToString(param.getValue());
+                    // collection query parameter value already escaped as part of parameterToPairs
+                    url.append(escapeString(param.getName())).append("=").append(value);
+                }
+            }
+        }
+
         return url.toString();
     }
 
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeApi.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeApi.java
index 61bc95032f8..6cf5cae059e 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeApi.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeApi.java
@@ -73,6 +73,7 @@ public class FakeApi {
         String localVarPath = "/fake/outer/boolean";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -103,7 +104,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -193,6 +194,7 @@ public class FakeApi {
         String localVarPath = "/fake/outer/composite";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -223,7 +225,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -313,6 +315,7 @@ public class FakeApi {
         String localVarPath = "/fake/outer/number";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -343,7 +346,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -433,6 +436,7 @@ public class FakeApi {
         String localVarPath = "/fake/outer/string";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -463,7 +467,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -553,6 +557,7 @@ public class FakeApi {
         String localVarPath = "/fake";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -583,7 +588,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "PATCH", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "PATCH", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -691,6 +696,7 @@ public class FakeApi {
         String localVarPath = "/fake";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -749,7 +755,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] { "http_basic_test" };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -901,12 +907,13 @@ public class FakeApi {
         String localVarPath = "/fake";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
         if (enumQueryStringArray != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("csv", "enum_query_string_array", enumQueryStringArray));
+        localVarCollectionQueryParams.addAll(apiClient.parameterToPairs("csv", "enum_query_string_array", enumQueryStringArray));
         if (enumQueryString != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("", "enum_query_string", enumQueryString));
+        localVarQueryParams.addAll(apiClient.parameterToPair("enum_query_string", enumQueryString));
         if (enumQueryInteger != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("", "enum_query_integer", enumQueryInteger));
+        localVarQueryParams.addAll(apiClient.parameterToPair("enum_query_integer", enumQueryInteger));
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
         if (enumHeaderStringArray != null)
@@ -947,7 +954,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -1055,6 +1062,7 @@ public class FakeApi {
         String localVarPath = "/fake/jsonFormData";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -1089,7 +1097,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeClassnameTags123Api.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeClassnameTags123Api.java
index ea7a08b189f..99d4beeaf43 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeClassnameTags123Api.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/FakeClassnameTags123Api.java
@@ -69,6 +69,7 @@ public class FakeClassnameTags123Api {
         String localVarPath = "/fake_classname_test";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -99,7 +100,7 @@ public class FakeClassnameTags123Api {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "PATCH", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "PATCH", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/PetApi.java
index aaf615a09ec..e375ad58a34 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/PetApi.java
@@ -71,6 +71,7 @@ public class PetApi {
         String localVarPath = "/pet";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -101,7 +102,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -194,6 +195,7 @@ public class PetApi {
             .replaceAll("\\{" + "petId" + "\\}", apiClient.escapeString(petId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
         if (apiKey != null)
@@ -226,7 +228,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -320,8 +322,9 @@ public class PetApi {
         String localVarPath = "/pet/findByStatus";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
         if (status != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("csv", "status", status));
+        localVarCollectionQueryParams.addAll(apiClient.parameterToPairs("csv", "status", status));
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -352,7 +355,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -447,8 +450,9 @@ public class PetApi {
         String localVarPath = "/pet/findByTags";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
         if (tags != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("csv", "tags", tags));
+        localVarCollectionQueryParams.addAll(apiClient.parameterToPairs("csv", "tags", tags));
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -479,7 +483,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -575,6 +579,7 @@ public class PetApi {
             .replaceAll("\\{" + "petId" + "\\}", apiClient.escapeString(petId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -605,7 +610,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "api_key" };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -700,6 +705,7 @@ public class PetApi {
         String localVarPath = "/pet";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -730,7 +736,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "PUT", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "PUT", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -824,6 +830,7 @@ public class PetApi {
             .replaceAll("\\{" + "petId" + "\\}", apiClient.escapeString(petId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -858,7 +865,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -958,6 +965,7 @@ public class PetApi {
             .replaceAll("\\{" + "petId" + "\\}", apiClient.escapeString(petId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -992,7 +1000,7 @@ public class PetApi {
         }
 
         String[] localVarAuthNames = new String[] { "petstore_auth" };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/StoreApi.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/StoreApi.java
index 0b1d4c12323..29d757735aa 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/StoreApi.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/StoreApi.java
@@ -70,6 +70,7 @@ public class StoreApi {
             .replaceAll("\\{" + "order_id" + "\\}", apiClient.escapeString(orderId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -100,7 +101,7 @@ public class StoreApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -190,6 +191,7 @@ public class StoreApi {
         String localVarPath = "/store/inventory";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -220,7 +222,7 @@ public class StoreApi {
         }
 
         String[] localVarAuthNames = new String[] { "api_key" };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -308,6 +310,7 @@ public class StoreApi {
             .replaceAll("\\{" + "order_id" + "\\}", apiClient.escapeString(orderId.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -338,7 +341,7 @@ public class StoreApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -433,6 +436,7 @@ public class StoreApi {
         String localVarPath = "/store/order";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -463,7 +467,7 @@ public class StoreApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
diff --git a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/UserApi.java
index a0d51095ef0..1f38895790c 100644
--- a/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/io/swagger/client/api/UserApi.java
@@ -69,6 +69,7 @@ public class UserApi {
         String localVarPath = "/user";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -99,7 +100,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -190,6 +191,7 @@ public class UserApi {
         String localVarPath = "/user/createWithArray";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -220,7 +222,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -311,6 +313,7 @@ public class UserApi {
         String localVarPath = "/user/createWithList";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -341,7 +344,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -433,6 +436,7 @@ public class UserApi {
             .replaceAll("\\{" + "username" + "\\}", apiClient.escapeString(username.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -463,7 +467,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -555,6 +559,7 @@ public class UserApi {
             .replaceAll("\\{" + "username" + "\\}", apiClient.escapeString(username.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -585,7 +590,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -681,10 +686,11 @@ public class UserApi {
         String localVarPath = "/user/login";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
         if (username != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("", "username", username));
+        localVarQueryParams.addAll(apiClient.parameterToPair("username", username));
         if (password != null)
-        localVarQueryParams.addAll(apiClient.parameterToPairs("", "password", password));
+        localVarQueryParams.addAll(apiClient.parameterToPair("password", password));
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -715,7 +721,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -817,6 +823,7 @@ public class UserApi {
         String localVarPath = "/user/logout";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -847,7 +854,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
@@ -932,6 +939,7 @@ public class UserApi {
             .replaceAll("\\{" + "username" + "\\}", apiClient.escapeString(username.toString()));
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -962,7 +970,7 @@ public class UserApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "PUT", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "PUT", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")
diff --git a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/FakeApi.java b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/FakeApi.java
index 7edb5a7ceef..6cf5cae059e 100644
--- a/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/FakeApi.java
+++ b/samples/client/petstore/java/okhttp-gson/src/main/java/io/swagger/client/api/FakeApi.java
@@ -1062,6 +1062,7 @@ public class FakeApi {
         String localVarPath = "/fake/jsonFormData";
 
         List<Pair> localVarQueryParams = new ArrayList<Pair>();
+        List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
 
         Map<String, String> localVarHeaderParams = new HashMap<String, String>();
 
@@ -1096,7 +1097,7 @@ public class FakeApi {
         }
 
         String[] localVarAuthNames = new String[] {  };
-        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
+        return apiClient.buildCall(localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAuthNames, progressRequestListener);
     }
     
     @SuppressWarnings("rawtypes")