restTemplate exchange often leads into 400 Error

Question

In my Android app I try to make a GET request via restTemplate.exchange but it leads very often into a 400 error very seldom it's a 200 response.

GET request for "http://someURL/items/modified/2018-12-20T12%253A47%253A43%252B01%253A00" resulted in 400 (); invoking error handler

org.springframework.web.client.HttpClientErrorException: 400

I tried to do the request with encoded and decoded parameter but it's the same problem. The only thing what changes is the timestamp in the request. I don't think it's a backend problem, because I did a couple requests via Swagger and Postman on the same interface and all of them worked without a problem. I also tried to update spring-android to version 2.0.0.M3 but still the same problem.

String url = ServiceAppConstants.HOSTNAME + ServiceAppConstants.REST_ITEMS_MODIFIED +                             URLEncoder.encode(lastSynchronisationDate);
try {
  HttpEntity<String> httpEntity = RestServiceUtils.getHttpEntity(context);
  RestTemplate restTemplate = new RestTemplate();
  restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());

   // runs in the error here
   ResponseEntity<ArrayList> response = restTemplate.exchange(url, HttpMethod.GET, httpEntity, ArrayList.class); 
   items= response.getBody();
   items = mapper.convertValue(items, new TypeReference<List<Items>>(){});
} catch (RestClientException e) {
    /* do stuff */
}

to set the token

@NonNull
public static HttpEntity<String> getHttpEntity(Context context) {
    UserStorage userStorage = new UserStorage(context);
    HttpHeaders headers = new HttpHeaders();
    try {
        String token = userStorage.getJsonWebToken();
        headers.set(ServiceAppConstants.HEADER_SECURITY_TOKEN, token);
    }catch (Exception ex){
        Log.e(RestServiceUtils.class.getName(), "Could not get json web token", ex);
    }
    return new HttpEntity<String>("parameters", headers);
}

This is how the request looks like in the android profiler

This is how the request looks like if it's send by swagger

Answer 1

use new HttpEntity(headers); (without "parameters")

the "parameters" string is the request body according to HttpEntity documentation that might caused the problem.