Do not apply content-type header if no request body (#6648)

* Do not apply content-type header if no request body

* Set content-type header if there are form params

* Add tests

* Run update script

* Regenerated sample clients

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/PetApi.java

@@ -37,7 +37,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("DELETE /pet/{petId}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
     "api_key: {apiKey}"
   })
@@ -51,7 +50,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("GET /pet/findByStatus?status={status}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   List<Pet> findPetsByStatus(@Param("status") List<String> status);
@@ -73,7 +71,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("GET /pet/findByStatus?status={status}")
   @Headers({
-  "Content-Type: application/json",
   "Accept: application/json",
   })
   List<Pet> findPetsByStatus(@QueryMap(encoded=true) Map<String, Object> queryParams);
@@ -97,7 +94,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("GET /pet/findByTags?tags={tags}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   List<Pet> findPetsByTags(@Param("tags") List<String> tags);
@@ -119,7 +115,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("GET /pet/findByTags?tags={tags}")
   @Headers({
-  "Content-Type: application/json",
   "Accept: application/json",
   })
   List<Pet> findPetsByTags(@QueryMap(encoded=true) Map<String, Object> queryParams);
@@ -143,7 +138,6 @@ public interface PetApi extends ApiClient.Api {
    */
   @RequestLine("GET /pet/{petId}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   Pet getPetById(@Param("petId") Long petId);

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/StoreApi.java

@@ -22,7 +22,6 @@ public interface StoreApi extends ApiClient.Api {
    */
   @RequestLine("DELETE /store/order/{orderId}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   void deleteOrder(@Param("orderId") String orderId);
@@ -34,7 +33,6 @@ public interface StoreApi extends ApiClient.Api {
    */
   @RequestLine("GET /store/inventory")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   Map<String, Integer> getInventory();
@@ -47,7 +45,6 @@ public interface StoreApi extends ApiClient.Api {
    */
   @RequestLine("GET /store/order/{orderId}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   Order getOrderById(@Param("orderId") Long orderId);

samples/client/petstore/java/feign/src/main/java/io/swagger/client/api/UserApi.java

@@ -58,7 +58,6 @@ public interface UserApi extends ApiClient.Api {
    */
   @RequestLine("DELETE /user/{username}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   void deleteUser(@Param("username") String username);
@@ -71,7 +70,6 @@ public interface UserApi extends ApiClient.Api {
    */
   @RequestLine("GET /user/{username}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   User getUserByName(@Param("username") String username);
@@ -85,7 +83,6 @@ public interface UserApi extends ApiClient.Api {
    */
   @RequestLine("GET /user/login?username={username}&password={password}")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   String loginUser(@Param("username") String username, @Param("password") String password);
@@ -108,7 +105,6 @@ public interface UserApi extends ApiClient.Api {
    */
   @RequestLine("GET /user/login?username={username}&password={password}")
   @Headers({
-  "Content-Type: application/json",
   "Accept: application/json",
   })
   String loginUser(@QueryMap(encoded=true) Map<String, Object> queryParams);
@@ -134,7 +130,6 @@ public interface UserApi extends ApiClient.Api {
    */
   @RequestLine("GET /user/logout")
   @Headers({
-    "Content-Type: application/json",
     "Accept: application/json",
   })
   void logoutUser();

samples/client/petstore/java/retrofit2rx/pom.xml

@@ -235,7 +235,6 @@
             </dependency>
 
 
-
         <!-- test dependencies -->
         <dependency>
             <groupId>junit</groupId>

samples/client/petstore/java/retrofit2rx2/pom.xml

@@ -235,7 +235,6 @@
             </dependency>
 
 
-
         <!-- test dependencies -->
         <dependency>
             <groupId>junit</groupId>