[Java] Respect User Supplied Header Params (#20042)

* [Java] Respect User Supplied Header Params

* remove if `dynamicOperations` true

bin/utils/test_file_list.yaml

@@ -12,6 +12,6 @@
 - filename: "samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java"
   sha256: e673d9928c8eb848262d0116fe0d28db832e128671a810a7c966d06d90cb9b63
 - filename: "samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/api/PetApiTest.java"
-  sha256: 0d64cdc11809a7b5b952ccdad2bd91bd0045b3894d6fabf3e368fa0be12b8217
+  sha256: 8b1b8f2a2ad00ccb090873a94a5f73e328b98317d2ec715f53bd7a1accb2a023
 - filename: "samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/model/PetTest.java"
   sha256: a1f8a70bf7b0c382a8def5bacf7b1fb189e687fabb40235aa799001e0597f545

modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/api.mustache

@@ -180,12 +180,6 @@ public class {{classname}} {
 
         {{/isQueryParam}}
         {{/constantParams}}
-        {{#headerParams}}
-        if ({{paramName}} != null) {
-            localVarHeaderParams.put("{{baseName}}", localVarApiClient.parameterToString({{paramName}}));
-        }
-
-        {{/headerParams}}
         {{#constantParams}}
         {{#isHeaderParam}}
         // Set client side default value of Header Param "{{baseName}}".
@@ -230,6 +224,15 @@ public class {{classname}} {
         if (localVarContentType != null) {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
+        {{^dynamicOperations}}
+        {{#headerParams}}
+
+        if ({{paramName}} != null) {
+            localVarHeaderParams.put("{{baseName}}", localVarApiClient.parameterToString({{paramName}}));
+        }
+
+        {{/headerParams}}
+        {{/dynamicOperations}}
 
         String[] localVarAuthNames = new String[] { {{#withAWSV4Signature}}"AWS4Auth"{{/withAWSV4Signature}}{{#authMethods}}{{#-first}}{{#withAWSV4Signature}}, {{/withAWSV4Signature}}{{/-first}}"{{name}}"{{^-last}}, {{/-last}}{{/authMethods}} };
         return localVarApiClient.buildCall(basePath, localVarPath, {{^dynamicOperations}}"{{httpMethod}}"{{/dynamicOperations}}{{#dynamicOperations}}apiOperation.getMethod(){{/dynamicOperations}}, localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);

modules/openapi-generator/src/test/resources/3_0/java/petstore-with-fake-endpoints-models-for-testing-okhttp-gson.yaml

@@ -258,6 +258,13 @@ paths:
           schema:
             type: integer
             format: int64
+        - name: Content-Type
+          in: header
+          style: simple
+          description: Content type header parameter
+          required: false
+          schema:
+            type: string
       responses:
         '200':
           description: successful operation

samples/client/echo_api/java/okhttp-gson-user-defined-templates/src/main/java/org/openapitools/client/api/PetApi.java

@@ -242,10 +242,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -260,6 +256,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/api/HeaderApi.java

@@ -113,26 +113,6 @@ public class HeaderApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (integerHeader != null) {
-            localVarHeaderParams.put("integer_header", localVarApiClient.parameterToString(integerHeader));
-        }
-
-        if (booleanHeader != null) {
-            localVarHeaderParams.put("boolean_header", localVarApiClient.parameterToString(booleanHeader));
-        }
-
-        if (stringHeader != null) {
-            localVarHeaderParams.put("string_header", localVarApiClient.parameterToString(stringHeader));
-        }
-
-        if (enumNonrefStringHeader != null) {
-            localVarHeaderParams.put("enum_nonref_string_header", localVarApiClient.parameterToString(enumNonrefStringHeader));
-        }
-
-        if (enumRefStringHeader != null) {
-            localVarHeaderParams.put("enum_ref_string_header", localVarApiClient.parameterToString(enumRefStringHeader));
-        }
-
         final String[] localVarAccepts = {
             "text/plain"
         };
@@ -148,6 +128,31 @@ public class HeaderApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (integerHeader != null) {
+            localVarHeaderParams.put("integer_header", localVarApiClient.parameterToString(integerHeader));
+        }
+
+
+        if (booleanHeader != null) {
+            localVarHeaderParams.put("boolean_header", localVarApiClient.parameterToString(booleanHeader));
+        }
+
+
+        if (stringHeader != null) {
+            localVarHeaderParams.put("string_header", localVarApiClient.parameterToString(stringHeader));
+        }
+
+
+        if (enumNonrefStringHeader != null) {
+            localVarHeaderParams.put("enum_nonref_string_header", localVarApiClient.parameterToString(enumNonrefStringHeader));
+        }
+
+
+        if (enumRefStringHeader != null) {
+            localVarHeaderParams.put("enum_ref_string_header", localVarApiClient.parameterToString(enumRefStringHeader));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -806,10 +806,6 @@ public class FakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (refToUuid != null) {
-            localVarHeaderParams.put("ref_to_uuid", localVarApiClient.parameterToString(refToUuid));
-        }
-
         final String[] localVarAccepts = {
             "text/plain"
         };
@@ -825,6 +821,11 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (refToUuid != null) {
+            localVarHeaderParams.put("ref_to_uuid", localVarApiClient.parameterToString(refToUuid));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -932,10 +933,6 @@ public class FakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (refToAnyof != null) {
-            localVarHeaderParams.put("ref_to_anyof", localVarApiClient.parameterToString(refToAnyof));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -950,6 +947,11 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (refToAnyof != null) {
+            localVarHeaderParams.put("ref_to_anyof", localVarApiClient.parameterToString(refToAnyof));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -1053,10 +1055,6 @@ public class FakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (refToOneof != null) {
-            localVarHeaderParams.put("ref_to_oneof", localVarApiClient.parameterToString(refToOneof));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -1071,6 +1069,11 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (refToOneof != null) {
+            localVarHeaderParams.put("ref_to_oneof", localVarApiClient.parameterToString(refToOneof));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/api/PetApi.java

@@ -242,10 +242,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -260,6 +256,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-awsv4signature/src/main/java/org/openapitools/client/api/PetApi.java

@@ -242,10 +242,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -260,6 +256,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "AWS4Auth", "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-group-parameter/src/main/java/org/openapitools/client/api/PetApi.java

@@ -259,10 +259,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -277,6 +273,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-nullable-required/src/main/java/org/openapitools/client/api/PetApi.java

@@ -232,10 +232,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -250,6 +246,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/api/AnotherFakeApi.java

@@ -111,10 +111,6 @@ public class AnotherFakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (uuidTest != null) {
-            localVarHeaderParams.put("uuid_test", localVarApiClient.parameterToString(uuidTest));
-        }
-
         final String[] localVarAccepts = {
             "application/json"
         };
@@ -131,6 +127,11 @@ public class AnotherFakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (uuidTest != null) {
+            localVarHeaderParams.put("uuid_test", localVarApiClient.parameterToString(uuidTest));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "PATCH", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -1357,14 +1357,6 @@ public class FakeApi {
             localVarQueryParams.addAll(localVarApiClient.parameterToPair("enum_query_double", enumQueryDouble));
         }
 
-        if (enumHeaderStringArray != null) {
-            localVarHeaderParams.put("enum_header_string_array", localVarApiClient.parameterToString(enumHeaderStringArray));
-        }
-
-        if (enumHeaderString != null) {
-            localVarHeaderParams.put("enum_header_string", localVarApiClient.parameterToString(enumHeaderString));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -1380,6 +1372,16 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (enumHeaderStringArray != null) {
+            localVarHeaderParams.put("enum_header_string_array", localVarApiClient.parameterToString(enumHeaderStringArray));
+        }
+
+
+        if (enumHeaderString != null) {
+            localVarHeaderParams.put("enum_header_string", localVarApiClient.parameterToString(enumHeaderString));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -1506,14 +1508,6 @@ public class FakeApi {
             localVarQueryParams.addAll(localVarApiClient.parameterToPair("int64_group", int64Group));
         }
 
-        if (requiredBooleanGroup != null) {
-            localVarHeaderParams.put("required_boolean_group", localVarApiClient.parameterToString(requiredBooleanGroup));
-        }
-
-        if (booleanGroup != null) {
-            localVarHeaderParams.put("boolean_group", localVarApiClient.parameterToString(booleanGroup));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -1528,6 +1522,16 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (requiredBooleanGroup != null) {
+            localVarHeaderParams.put("required_boolean_group", localVarApiClient.parameterToString(requiredBooleanGroup));
+        }
+
+
+        if (booleanGroup != null) {
+            localVarHeaderParams.put("boolean_group", localVarApiClient.parameterToString(booleanGroup));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-parcelableModel/src/main/java/org/openapitools/client/api/PetApi.java

@@ -238,10 +238,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -256,6 +252,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-swagger1/src/main/java/org/openapitools/client/api/CommonApi.java

@@ -721,10 +721,6 @@ public class CommonApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -739,6 +735,11 @@ public class CommonApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson-swagger2/src/main/java/org/openapitools/client/api/PetApi.java

@@ -242,10 +242,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -260,6 +256,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson/api/openapi.yaml

@@ -300,6 +300,14 @@ paths:
           format: int64
           type: integer
         style: simple
+      - description: Content type header parameter
+        explode: false
+        in: header
+        name: Content-Type
+        required: false
+        schema:
+          type: string
+        style: simple
       requestBody:
         content:
           multipart/form-data:

samples/client/petstore/java/okhttp-gson/docs/PetApi.md

@@ -496,7 +496,7 @@ null (empty response body)
 
 <a id="uploadFile"></a>
 # **uploadFile**
-> ModelApiResponse uploadFile(petId, additionalMetadata, _file)
+> ModelApiResponse uploadFile(petId, contentType, additionalMetadata, _file)
 
 uploads an image
 
@@ -523,10 +523,11 @@ public class Example {
 
     PetApi apiInstance = new PetApi(defaultClient);
     Long petId = 56L; // Long | ID of pet to update
+    String contentType = "contentType_example"; // String | Content type header parameter
     String additionalMetadata = "additionalMetadata_example"; // String | Additional data to pass to server
     File _file = new File("/path/to/file"); // File | file to upload
     try {
-      ModelApiResponse result = apiInstance.uploadFile(petId, additionalMetadata, _file);
+      ModelApiResponse result = apiInstance.uploadFile(petId, contentType, additionalMetadata, _file);
       System.out.println(result);
     } catch (ApiException e) {
       System.err.println("Exception when calling PetApi#uploadFile");
@@ -544,6 +545,7 @@ public class Example {
 | Name | Type | Description  | Notes |
 |------------- | ------------- | ------------- | -------------|
 | **petId** | **Long**| ID of pet to update | |
+| **contentType** | **String**| Content type header parameter | [optional] |
 | **additionalMetadata** | **String**| Additional data to pass to server | [optional] |
 | **_file** | **File**| file to upload | [optional] |
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/AnotherFakeApi.java

@@ -233,10 +233,6 @@ public class AnotherFakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (array != null) {
-            localVarHeaderParams.put("array", localVarApiClient.parameterToString(array));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -251,6 +247,11 @@ public class AnotherFakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (array != null) {
+            localVarHeaderParams.put("array", localVarApiClient.parameterToString(array));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -354,10 +355,6 @@ public class AnotherFakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (stringNumber != null) {
-            localVarHeaderParams.put("string_number", localVarApiClient.parameterToString(stringNumber));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -372,6 +369,11 @@ public class AnotherFakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (stringNumber != null) {
+            localVarHeaderParams.put("string_number", localVarApiClient.parameterToString(stringNumber));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -475,10 +477,6 @@ public class AnotherFakeApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (acceptLanguage != null) {
-            localVarHeaderParams.put("Accept-Language", localVarApiClient.parameterToString(acceptLanguage));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -494,6 +492,11 @@ public class AnotherFakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (acceptLanguage != null) {
+            localVarHeaderParams.put("Accept-Language", localVarApiClient.parameterToString(acceptLanguage));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -1197,14 +1197,6 @@ public class FakeApi {
             localVarQueryParams.addAll(localVarApiClient.parameterToPair("type", type));
         }
 
-        if (underscoreType != null) {
-            localVarHeaderParams.put("_type", localVarApiClient.parameterToString(underscoreType));
-        }
-
-        if (typeWithUnderscore != null) {
-            localVarHeaderParams.put("type_", localVarApiClient.parameterToString(typeWithUnderscore));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -1219,6 +1211,16 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (underscoreType != null) {
+            localVarHeaderParams.put("_type", localVarApiClient.parameterToString(underscoreType));
+        }
+
+
+        if (typeWithUnderscore != null) {
+            localVarHeaderParams.put("type_", localVarApiClient.parameterToString(typeWithUnderscore));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -2105,14 +2107,6 @@ public class FakeApi {
             localVarQueryParams.addAll(localVarApiClient.parameterToPair("enum_query_double", enumQueryDouble));
         }
 
-        if (enumHeaderStringArray != null) {
-            localVarHeaderParams.put("enum_header_string_array", localVarApiClient.parameterToString(enumHeaderStringArray));
-        }
-
-        if (enumHeaderString != null) {
-            localVarHeaderParams.put("enum_header_string", localVarApiClient.parameterToString(enumHeaderString));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -2128,6 +2122,16 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (enumHeaderStringArray != null) {
+            localVarHeaderParams.put("enum_header_string_array", localVarApiClient.parameterToString(enumHeaderStringArray));
+        }
+
+
+        if (enumHeaderString != null) {
+            localVarHeaderParams.put("enum_header_string", localVarApiClient.parameterToString(enumHeaderString));
+        }
+
+
         String[] localVarAuthNames = new String[] {  };
         return localVarApiClient.buildCall(basePath, localVarPath, "GET", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -2254,14 +2258,6 @@ public class FakeApi {
             localVarQueryParams.addAll(localVarApiClient.parameterToPair("int64_group", int64Group));
         }
 
-        if (requiredBooleanGroup != null) {
-            localVarHeaderParams.put("required_boolean_group", localVarApiClient.parameterToString(requiredBooleanGroup));
-        }
-
-        if (booleanGroup != null) {
-            localVarHeaderParams.put("boolean_group", localVarApiClient.parameterToString(booleanGroup));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -2276,6 +2272,16 @@ public class FakeApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (requiredBooleanGroup != null) {
+            localVarHeaderParams.put("required_boolean_group", localVarApiClient.parameterToString(requiredBooleanGroup));
+        }
+
+
+        if (booleanGroup != null) {
+            localVarHeaderParams.put("boolean_group", localVarApiClient.parameterToString(booleanGroup));
+        }
+
+
         String[] localVarAuthNames = new String[] { "bearer_test" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/api/PetApi.java

@@ -232,10 +232,6 @@ public class PetApi {
         Map<String, String> localVarCookieParams = new HashMap<String, String>();
         Map<String, Object> localVarFormParams = new HashMap<String, Object>();
 
-        if (apiKey != null) {
-            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
-        }
-
         final String[] localVarAccepts = {
         };
         final String localVarAccept = localVarApiClient.selectHeaderAccept(localVarAccepts);
@@ -250,6 +246,11 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (apiKey != null) {
+            localVarHeaderParams.put("api_key", localVarApiClient.parameterToString(apiKey));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "DELETE", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
@@ -987,6 +988,7 @@ public class PetApi {
     /**
      * Build call for uploadFile
      * @param petId ID of pet to update (required)
+     * @param contentType Content type header parameter (optional)
      * @param additionalMetadata Additional data to pass to server (optional)
      * @param _file file to upload (optional)
      * @param _callback Callback for upload/download progress
@@ -998,7 +1000,7 @@ public class PetApi {
         <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
      </table>
      */
-    public okhttp3.Call uploadFileCall(Long petId, String additionalMetadata, File _file, final ApiCallback _callback) throws ApiException {
+    public okhttp3.Call uploadFileCall(Long petId, String contentType, String additionalMetadata, File _file, final ApiCallback _callback) throws ApiException {
         String basePath = null;
         // Operation Servers
         String[] localBasePaths = new String[] {  };
@@ -1048,18 +1050,23 @@ public class PetApi {
             localVarHeaderParams.put("Content-Type", localVarContentType);
         }
 
+        if (contentType != null) {
+            localVarHeaderParams.put("Content-Type", localVarApiClient.parameterToString(contentType));
+        }
+
+
         String[] localVarAuthNames = new String[] { "petstore_auth" };
         return localVarApiClient.buildCall(basePath, localVarPath, "POST", localVarQueryParams, localVarCollectionQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAuthNames, _callback);
     }
 
     @SuppressWarnings("rawtypes")
-    private okhttp3.Call uploadFileValidateBeforeCall(Long petId, String additionalMetadata, File _file, final ApiCallback _callback) throws ApiException {
+    private okhttp3.Call uploadFileValidateBeforeCall(Long petId, String contentType, String additionalMetadata, File _file, final ApiCallback _callback) throws ApiException {
         // verify the required parameter 'petId' is set
         if (petId == null) {
             throw new ApiException("Missing the required parameter 'petId' when calling uploadFile(Async)");
         }
 
-        return uploadFileCall(petId, additionalMetadata, _file, _callback);
+        return uploadFileCall(petId, contentType, additionalMetadata, _file, _callback);
 
     }
 
@@ -1067,6 +1074,7 @@ public class PetApi {
      * uploads an image
      * 
      * @param petId ID of pet to update (required)
+     * @param contentType Content type header parameter (optional)
      * @param additionalMetadata Additional data to pass to server (optional)
      * @param _file file to upload (optional)
      * @return ModelApiResponse
@@ -1077,8 +1085,8 @@ public class PetApi {
         <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
      </table>
      */
-    public ModelApiResponse uploadFile(Long petId, String additionalMetadata, File _file) throws ApiException {
+    public ModelApiResponse uploadFile(Long petId, String contentType, String additionalMetadata, File _file) throws ApiException {
-        ApiResponse<ModelApiResponse> localVarResp = uploadFileWithHttpInfo(petId, additionalMetadata, _file);
+        ApiResponse<ModelApiResponse> localVarResp = uploadFileWithHttpInfo(petId, contentType, additionalMetadata, _file);
         return localVarResp.getData();
     }
 
@@ -1086,6 +1094,7 @@ public class PetApi {
      * uploads an image
      * 
      * @param petId ID of pet to update (required)
+     * @param contentType Content type header parameter (optional)
      * @param additionalMetadata Additional data to pass to server (optional)
      * @param _file file to upload (optional)
      * @return ApiResponse&lt;ModelApiResponse&gt;
@@ -1096,8 +1105,8 @@ public class PetApi {
         <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
      </table>
      */
-    public ApiResponse<ModelApiResponse> uploadFileWithHttpInfo(Long petId, String additionalMetadata, File _file) throws ApiException {
+    public ApiResponse<ModelApiResponse> uploadFileWithHttpInfo(Long petId, String contentType, String additionalMetadata, File _file) throws ApiException {
-        okhttp3.Call localVarCall = uploadFileValidateBeforeCall(petId, additionalMetadata, _file, null);
+        okhttp3.Call localVarCall = uploadFileValidateBeforeCall(petId, contentType, additionalMetadata, _file, null);
         Type localVarReturnType = new TypeToken<ModelApiResponse>(){}.getType();
         return localVarApiClient.execute(localVarCall, localVarReturnType);
     }
@@ -1106,6 +1115,7 @@ public class PetApi {
      * uploads an image (asynchronously)
      * 
      * @param petId ID of pet to update (required)
+     * @param contentType Content type header parameter (optional)
      * @param additionalMetadata Additional data to pass to server (optional)
      * @param _file file to upload (optional)
      * @param _callback The callback to be executed when the API call finishes
@@ -1117,9 +1127,9 @@ public class PetApi {
         <tr><td> 200 </td><td> successful operation </td><td>  -  </td></tr>
      </table>
      */
-    public okhttp3.Call uploadFileAsync(Long petId, String additionalMetadata, File _file, final ApiCallback<ModelApiResponse> _callback) throws ApiException {
+    public okhttp3.Call uploadFileAsync(Long petId, String contentType, String additionalMetadata, File _file, final ApiCallback<ModelApiResponse> _callback) throws ApiException {
 
-        okhttp3.Call localVarCall = uploadFileValidateBeforeCall(petId, additionalMetadata, _file, _callback);
+        okhttp3.Call localVarCall = uploadFileValidateBeforeCall(petId, contentType, additionalMetadata, _file, _callback);
         Type localVarReturnType = new TypeToken<ModelApiResponse>(){}.getType();
         localVarApiClient.executeAsync(localVarCall, localVarReturnType, _callback);
         return localVarCall;

samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/api/PetApiTest.java

@@ -399,7 +399,22 @@ public class PetApiTest {
         writer.write("Hello world!");
         writer.close();
 
-        api.uploadFile(pet.getId(), "a test file", new File(file.getAbsolutePath()));
+        // respect user supplied content type
+        ApiResponse formDataResponse = api.uploadFileWithHttpInfo(pet.getId(), "multipart/form-data", "a test file", new File(file.getAbsolutePath()));
+        assertEquals(200, formDataResponse.getStatusCode());
+
+        // use default content type
+        ApiResponse defaultResponse = api.uploadFileWithHttpInfo(pet.getId(), null, "a test file", new File(file.getAbsolutePath()));
+        assertEquals(200, defaultResponse.getStatusCode());
+
+        try {
+            // use invalid content type
+            api.uploadFileWithHttpInfo(pet.getId(), "image/jpeg", "a test file", new File(file.getAbsolutePath()));
+        } catch (ApiException e) {
+            LOG.info("Code: {}. Message: {}", e.getCode(), e.getMessage());
+            assertEquals(415, e.getCode());
+        }
+        
         api.deletePet(pet.getId(), null);
     }