@Test
public void test_convetToJson_successfully() {

    String jsonStr = "{\"username\":\"testuser\",\"password\":\"testuser\"}";
    Map<String,Object> jsonmap = new LinkedHashMap<>();
    jsonmap.put("username", "testuser");
    jsonmap.put("password", "testuser");
    String actualResponse = ControllerUtil.convetToJson(jsonmap);
    assertEquals(jsonStr, actualResponse);
}