JSON Object as @RequestBody on Spring 4.16

So i have this android application that send jsonObject for a jsonObjectRequest (I'm using volley) with POST method. The JSON file was sent but the server (this is where i'm using Spring btw) is not responding. The code pretty much like these.

Android Code:

JSONObject jsonObject = new JSONObject(data);

final JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.POST, url, jsonObject, new Response.Listener<JSONObject>() {
   @Override
   public void onResponse(JSONObject response) {
      try {
          userToken = response.getString(TAG_TOKEN);
   //  blablabla

Server Code:

@RestController
@RequestMapping("/auth/")
public class AuthController {

String userEmail;
String userPassword;

@RequestMapping(value = "/login", method = RequestMethod.POST)
public LoginResponse loginResponse(@RequestBody Auth auth){

    userEmail = auth.getEmail();
    userPassword = auth.getPassword();
// blablabla

Auth Object:

public class Auth {

    private String email;
    private String password;

// blablabla

It seems like the server didn't receive the JsonObject from the android client correctly. (The server is able to send JSON to android client perfectly in another case, though). I'm using spring-4.16, jackson-core, jackson-annotation, jackson-databind (2.2.2). Thanks in advance!