title: Swagger for Play: DELETE request always returns "Invalid Json"
body: <p>I've just downloaded the last distro of Swagger-UI... and it looks like it no longer works when sending a DELETE request without JSON body &ndash; be aware that this worked fine with the previous version. Here below are my annotations:</p>
  
  <pre><code>@ApiOperation(
    httpMethod = "DELETE",
    nickname = "delete",
    value = "Deletes an user",
    response = classOf[Void])
  @ApiResponses(Array(
    new ApiResponse(code = 400, message = "Invalid user id"),
    new ApiResponse(code = 401, message = "Request not authorized"),
    new ApiResponse(code = 403, message = "User does not have required privileges"),
    new ApiResponse(code = 404, message = "User not found"),
    new ApiResponse(code = 412, message = "Authentication precondition failed"),
    new ApiResponse(code = 500, message = "Error processing delete user request")))
  def delete(
    @ApiParam(
      name = "userId",
      value = "The id of the user to delete",
      required = true)
      @PathParam("userId")
      userId: String) = SecuredAction.async { implicit request =&gt;
    ...
  }
  </code></pre>
  
  <p>Whenever I send a DELETE request, I always get the the following response (Bad request):</p>
  
  <pre><code>For request 'DELETE /auth/users/5392238c1e04001e04b384b4' [Invalid Json]
  </code></pre>
  
  <p>Again, I haven't modified my source code and if I rollback to the previous version of Swagger-UI it works as expected. Am I missing something? In case is there a workaround to make it work?</p>