diff --git a/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache b/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
index 9392277b52ce..bfa33ac07643 100644
--- a/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/ApiClient.mustache
@@ -243,60 +243,61 @@ public class ApiClient {
   /*
     Format to {@code Pair} objects.
   */
-  public Set<Pair> parameterToQueryParams(String collectionFormat, String name, Object value){
+  public Set<Pair> parameterToPairs(String collectionFormat, String name, Object value){
     Set<Pair> params = new HashSet<Pair>();
 
     // preconditions
     if (name == null || name.isEmpty()) return params;
 
     if (value == null) {
-      params.add(new Pair(name, value));
+      params.add(new Pair(name, ""));
       return params;
     }
 
-    Collection<String> valueCollection = null;
+    Collection valueCollection = null;
     if (value instanceof Collection) {
-      valueCollection = (Collection<String>) value;
-    }
-
-    if (valueCollection == null) {
-      params.add(new Pair(name, String.valueOf(value)));
-      return params;
-    } else if (valueCollection.isEmpty()) {
+      valueCollection = (Collection) value;
+    } else {
+      params.add(new Pair(name, parameterToString(value)));
       return params;
     }
 
+    if (valueCollection.isEmpty()){
+      return params;
+    }
+
+    // get the collection format
     collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv
 
-    if (collectionFormat.equals("csv")) {
-      params.add(new Pair(name, parameterToString(value)));
-    } else if (collectionFormat.equals("multi")) {
-      for (String item : valueCollection) {
-        params.add(new Pair(name, item));
+    // create the params based on the collection format
+    if (collectionFormat.equals("multi")) {
+      for (Object item : valueCollection) {
+        params.add(new Pair(name, parameterToString(item)));
       }
-    } else if (collectionFormat.equals("ssv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append(" ");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("tsv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("\t");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("pipes")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("|");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
+
+      return params;
     }
 
+    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 = "|";
+    }
+
+    StringBuilder sb = new StringBuilder() ;
+    for (Object item : valueCollection) {
+      sb.append(delimiter);
+      sb.append(parameterToString(item));
+    }
+
+    params.add(new Pair(name, sb.substring(1)));
+
     return params;
   }
 
diff --git a/modules/swagger-codegen/src/main/resources/Java/api.mustache b/modules/swagger-codegen/src/main/resources/Java/api.mustache
index 8d8709da1865..c279e4d223e8 100644
--- a/modules/swagger-codegen/src/main/resources/Java/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/Java/api.mustache
@@ -67,7 +67,7 @@ public class {{classname}} {
     Map<String, String> formParams = new HashMap<String, String>();
 
     {{#queryParams}}
-    queryParams.addAll(apiClient.parameterToQueryParams("{{#collectionFormat}}{{{collectionFormat}}}{{/collectionFormat}}", "{{baseName}}", {{paramName}}));
+    queryParams.addAll(apiClient.parameterToPairs("{{#collectionFormat}}{{{collectionFormat}}}{{/collectionFormat}}", "{{baseName}}", {{paramName}}));
     {{/queryParams}}
 
     {{#headerParams}}if ({{paramName}} != null)
diff --git a/modules/swagger-codegen/src/main/resources/android-java/api.mustache b/modules/swagger-codegen/src/main/resources/android-java/api.mustache
index 326f4fbac2c6..5113116deb84 100644
--- a/modules/swagger-codegen/src/main/resources/android-java/api.mustache
+++ b/modules/swagger-codegen/src/main/resources/android-java/api.mustache
@@ -66,7 +66,7 @@ public class {{classname}} {
     Map<String, String> formParams = new HashMap<String, String>();
 
     {{#queryParams}}
-    queryParams.addAll(ApiInvoker.parameterToQueryParams("{{#collectionFormat}}{{{collectionFormat}}}{{/collectionFormat}}", "{{baseName}}", {{paramName}}));
+    queryParams.addAll(ApiInvoker.parameterToPairs("{{#collectionFormat}}{{{collectionFormat}}}{{/collectionFormat}}", "{{baseName}}", {{paramName}}));
     {{/queryParams}}
 
     {{#headerParams}}
diff --git a/modules/swagger-codegen/src/main/resources/android-java/apiInvoker.mustache b/modules/swagger-codegen/src/main/resources/android-java/apiInvoker.mustache
index 61baf88e8ea9..c3bc2cd39c9d 100644
--- a/modules/swagger-codegen/src/main/resources/android-java/apiInvoker.mustache
+++ b/modules/swagger-codegen/src/main/resources/android-java/apiInvoker.mustache
@@ -137,60 +137,61 @@ public class ApiInvoker {
   /*
     Format to {@code Pair} objects.
   */
-  public Set<Pair> parameterToQueryParams(String collectionFormat, String name, Object value){
+  public static Set<Pair> parameterToPairs(String collectionFormat, String name, Object value){
     Set<Pair> params = new HashSet<Pair>();
 
     // preconditions
     if (name == null || name.isEmpty()) return params;
 
     if (value == null) {
-      params.add(new Pair(name, value));
+      params.add(new Pair(name, ""));
       return params;
     }
 
-    Collection<String> valueCollection = null;
+    Collection valueCollection = null;
     if (value instanceof Collection) {
-      valueCollection = (Collection<String>) value;
-    }
-
-    if (valueCollection == null) {
-      params.add(new Pair(name, String.valueOf(value)));
-      return params;
-    } else if (valueCollection.isEmpty()) {
+      valueCollection = (Collection) value;
+    } else {
+      params.add(new Pair(name, parameterToString(value)));
       return params;
     }
 
+    if (valueCollection.isEmpty()){
+      return params;
+    }
+
+    // get the collection format
     collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv
 
-    if (collectionFormat.equals("csv")) {
-      params.add(new Pair(name, parameterToString(value)));
-    } else if (collectionFormat.equals("multi")) {
-      for (String item : valueCollection) {
-        params.add(new Pair(name, item));
+    // create the params based on the collection format
+    if (collectionFormat.equals("multi")) {
+      for (Object item : valueCollection) {
+        params.add(new Pair(name, parameterToString(item)));
       }
-    } else if (collectionFormat.equals("ssv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append(" ");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("tsv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("\t");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("pipes")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("|");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
+
+      return params;
     }
 
+    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 = "|";
+    }
+
+    StringBuilder sb = new StringBuilder() ;
+    for (Object item : valueCollection) {
+      sb.append(delimiter);
+      sb.append(parameterToString(item));
+    }
+
+    params.add(new Pair(name, sb.substring(1)));
+
     return params;
   }
 
diff --git a/samples/client/petstore/android-java/src/main/java/io/swagger/client/ApiInvoker.java b/samples/client/petstore/android-java/src/main/java/io/swagger/client/ApiInvoker.java
index 73dc1ddc65b6..f831a54c14bc 100644
--- a/samples/client/petstore/android-java/src/main/java/io/swagger/client/ApiInvoker.java
+++ b/samples/client/petstore/android-java/src/main/java/io/swagger/client/ApiInvoker.java
@@ -137,60 +137,61 @@ public class ApiInvoker {
   /*
     Format to {@code Pair} objects.
   */
-  public Set<Pair> parameterToQueryParams(String collectionFormat, String name, Object value){
+  public static Set<Pair> parameterToPairs(String collectionFormat, String name, Object value){
     Set<Pair> params = new HashSet<Pair>();
 
     // preconditions
     if (name == null || name.isEmpty()) return params;
 
     if (value == null) {
-      params.add(new Pair(name, value));
+      params.add(new Pair(name, ""));
       return params;
     }
 
-    Collection<String> valueCollection = null;
+    Collection valueCollection = null;
     if (value instanceof Collection) {
-      valueCollection = (Collection<String>) value;
-    }
-
-    if (valueCollection == null) {
-      params.add(new Pair(name, String.valueOf(value)));
-      return params;
-    } else if (valueCollection.isEmpty()) {
+      valueCollection = (Collection) value;
+    } else {
+      params.add(new Pair(name, parameterToString(value)));
       return params;
     }
 
+    if (valueCollection.isEmpty()){
+      return params;
+    }
+
+    // get the collection format
     collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv
 
-    if (collectionFormat.equals("csv")) {
-      params.add(new Pair(name, parameterToString(value)));
-    } else if (collectionFormat.equals("multi")) {
-      for (String item : valueCollection) {
-        params.add(new Pair(name, item));
+    // create the params based on the collection format
+    if (collectionFormat.equals("multi")) {
+      for (Object item : valueCollection) {
+        params.add(new Pair(name, parameterToString(item)));
       }
-    } else if (collectionFormat.equals("ssv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append(" ");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("tsv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("\t");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("pipes")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("|");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
+
+      return params;
     }
 
+    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 = "|";
+    }
+
+    StringBuilder sb = new StringBuilder() ;
+    for (Object item : valueCollection) {
+      sb.append(delimiter);
+      sb.append(parameterToString(item));
+    }
+
+    params.add(new Pair(name, sb.substring(1)));
+
     return params;
   }
 
diff --git a/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/PetApi.java b/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/PetApi.java
index 7b7929965355..8580512c7426 100644
--- a/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/PetApi.java
+++ b/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/PetApi.java
@@ -168,7 +168,7 @@ public class PetApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(ApiInvoker.parameterToQueryParams("multi", "status", status));
+    queryParams.addAll(ApiInvoker.parameterToPairs("multi", "status", status));
     
 
     
@@ -224,7 +224,7 @@ public class PetApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(ApiInvoker.parameterToQueryParams("multi", "tags", tags));
+    queryParams.addAll(ApiInvoker.parameterToPairs("multi", "tags", tags));
     
 
     
diff --git a/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/UserApi.java b/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/UserApi.java
index 3b74f343299d..f8096cb2a87c 100644
--- a/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/UserApi.java
+++ b/samples/client/petstore/android-java/src/main/java/io/swagger/client/api/UserApi.java
@@ -223,9 +223,9 @@ public class UserApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(ApiInvoker.parameterToQueryParams("", "username", username));
+    queryParams.addAll(ApiInvoker.parameterToPairs("", "username", username));
     
-    queryParams.addAll(ApiInvoker.parameterToQueryParams("", "password", password));
+    queryParams.addAll(ApiInvoker.parameterToPairs("", "password", password));
     
 
     
diff --git a/samples/client/petstore/java/src/main/java/io/swagger/client/ApiClient.java b/samples/client/petstore/java/src/main/java/io/swagger/client/ApiClient.java
index cd801e0d763d..b0258026896b 100644
--- a/samples/client/petstore/java/src/main/java/io/swagger/client/ApiClient.java
+++ b/samples/client/petstore/java/src/main/java/io/swagger/client/ApiClient.java
@@ -242,60 +242,61 @@ public class ApiClient {
   /*
     Format to {@code Pair} objects.
   */
-  public Set<Pair> parameterToQueryParams(String collectionFormat, String name, Object value){
+  public Set<Pair> parameterToPairs(String collectionFormat, String name, Object value){
     Set<Pair> params = new HashSet<Pair>();
 
     // preconditions
     if (name == null || name.isEmpty()) return params;
 
     if (value == null) {
-      params.add(new Pair(name, value));
+      params.add(new Pair(name, ""));
       return params;
     }
 
-    Collection<String> valueCollection = null;
+    Collection valueCollection = null;
     if (value instanceof Collection) {
-      valueCollection = (Collection<String>) value;
-    }
-
-    if (valueCollection == null) {
-      params.add(new Pair(name, String.valueOf(value)));
-      return params;
-    } else if (valueCollection.isEmpty()) {
+      valueCollection = (Collection) value;
+    } else {
+      params.add(new Pair(name, parameterToString(value)));
       return params;
     }
 
+    if (valueCollection.isEmpty()){
+      return params;
+    }
+
+    // get the collection format
     collectionFormat = (collectionFormat == null || collectionFormat.isEmpty() ? "csv" : collectionFormat); // default: csv
 
-    if (collectionFormat.equals("csv")) {
-      params.add(new Pair(name, parameterToString(value)));
-    } else if (collectionFormat.equals("multi")) {
-      for (String item : valueCollection) {
-        params.add(new Pair(name, item));
+    // create the params based on the collection format
+    if (collectionFormat.equals("multi")) {
+      for (Object item : valueCollection) {
+        params.add(new Pair(name, parameterToString(item)));
       }
-    } else if (collectionFormat.equals("ssv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append(" ");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("tsv")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("\t");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
-    } else if (collectionFormat.equals("pipes")) {
-      StringBuilder sb = new StringBuilder() ;
-      for (String item : valueCollection) {
-        sb.append("|");
-        sb.append(item);
-      }
-      params.add(new Pair(name, sb.substring(1)));
+
+      return params;
     }
 
+    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 = "|";
+    }
+
+    StringBuilder sb = new StringBuilder() ;
+    for (Object item : valueCollection) {
+      sb.append(delimiter);
+      sb.append(parameterToString(item));
+    }
+
+    params.add(new Pair(name, sb.substring(1)));
+
     return params;
   }
 
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 85d87534175e..922084ec48f8 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
@@ -174,7 +174,7 @@ public class PetApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(apiClient.parameterToQueryParams("multi", "status", status));
+    queryParams.addAll(apiClient.parameterToPairs("multi", "status", status));
     
 
     
@@ -233,7 +233,7 @@ public class PetApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(apiClient.parameterToQueryParams("multi", "tags", tags));
+    queryParams.addAll(apiClient.parameterToPairs("multi", "tags", tags));
     
 
     
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 4a3a69fe3e43..a8e2fa37a85a 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
@@ -232,9 +232,9 @@ public class UserApi {
     Map<String, String> formParams = new HashMap<String, String>();
 
     
-    queryParams.addAll(apiClient.parameterToQueryParams("", "username", username));
+    queryParams.addAll(apiClient.parameterToPairs("", "username", username));
     
-    queryParams.addAll(apiClient.parameterToQueryParams("", "password", password));
+    queryParams.addAll(apiClient.parameterToPairs("", "password", password));