i want to post this data to the server. i an getting null response. what do get response from server
 {
    "test_id":5,
    "user_id":null,
    "org_id":2,
    "schedule_id":15,
    "group_id":null,
    "next_section_id":"",
    "current_section":
       {
        }
    }
i create interface
@POST("take_tests")
Call<Test_Responce> testRes (@Body JSONObject paramObject);
function
try {
            JSONObject paramObject = new JSONObject();
            JSONObject current_section = new JSONObject();
            paramObject.put("test_id", 5);
            paramObject.put("user_id", "null");
            paramObject.put("org_id", 2);
            paramObject.put("schedule_id", 15);
            paramObject.put("group_id", "null");
            paramObject.put("current_section",current_section);
            Call<Test_Responce> userCall = api_interface.testRes(paramObject);
            userCall.enqueue(new Callback<Test_Responce>() {
                @Override
                public void onResponse(Call<Test_Responce> call, Response<Test_Responce> response) {
                    if (response.isSuccessful()){
                        Toast.makeText(getApplicationContext(),"success",Toast.LENGTH_SHORT).show();
                    }else {
                        Toast.makeText(getApplicationContext(),"else",Toast.LENGTH_SHORT).show();
                    }
                }
                @Override
                public void onFailure(Call<Test_Responce> call, Throwable t) {
                    Toast.makeText(getApplicationContext(),"fail",Toast.LENGTH_SHORT).show();
                }
 
     
     
    