Post JSON Object as response to url

Good day everyone please I am supposed to send back a JSON object as a response from my service using RestTemplate but I am confused about where to add the JSON data with restTemplate.exchange() method.

Please see the code below. Thank you in advance.

JSONObject json= new JSONObject();

json.put("responseCode", 200);
json.put("responseMessage", "Transaction Successfully proceed");
json.put("responseData", transactionDetail.toJson());

RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);

HttpEntity<Object> entity = new HttpEntity<>(headers);

restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
MappingJackson2HttpMessageConverter jsonHttpMessageConverter = new MappingJackson2HttpMessageConverter();
        jsonHttpMessageConverter.getObjectMapper().configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
restTemplate.getMessageConverters().add(jsonHttpMessageConverter);

ResponseEntity<String> resultFromVGIL = restTemplate.exchange(bitbackCallBackUrl, HttpMethod.POST, entity, String.class);