How to write controller class to allow content-type: application/json and application/x-www-form-urlencoded

I am sending request to my controller class request as content-Type: application/json and application/x-www-form-urlencoded format It should allow both types.

below is my controller class.

@RequestMapping(value = "/home", method = RequestMethod.POST)
    public String getCustomer(@ModelAttribute HomeRequest homeRequestequest,
            HttpServletRequest request) {

        String response = homeService.getCustomerResponse(homeRequestequest, request);
         return response;
        }

In service class I written below code. Here I am calling another api

public String getCustomerResponse(@ModelAttribute HomeRequest homeRequest,
            HttpServletRequest request) {       
            String url="https://somthing---";
        HttpHeaders header = new HttpHeaders();
                header.add("Api-Key", "RTM");
                header.add("Accept", "application/json;v=3");
                header.setContentType(MediaType.APPLICATION_JSON);
      Gson gson = new Gson();
            messageRequest = gson.toJson(messageNotification);
            HttpEntity<?> entityRequest = new HttpEntity<Object>(messageRequest, header);
            Map<String, String> urlVariables = new HashMap<String, String>();
    return restTemplate.exchange(url, HttpMethod.POST, entityRequest, String.class,
                    urlVariables);

But when I am using request type as a application/x-www-form-urlencoded it is working but when I use request application/json this code is not working it is giving 400 response status. How to solve this issue.