public void login(Context context, String username, String password,
                      Response.Listener<User> listener, Response.ErrorListener errorListener,
                      String tag) {

        // URL
        String url = UrlHelper.BASE_URL + UrlHelper.LOGIN_RESOURCE;

        // HTTP Method
        int httpMethod = Request.Method.GET;

        // Body
        String body = null;

        // HTTP headers
        Map<String, String> headers = new LinkedHashMap<>();
        HTTPHeaderHelper.AddHTTPHeader(context, username, password, headers);

        // URL query params
        Map<String, String> params = null;

        // Create request
        Request<User> request = new GsonRequest<User>(httpMethod, url, User.class, body, headers, params, listener, errorListener);

        // set retry policy
        request.setRetryPolicy(new DefaultRetryPolicy(Constant.SOCKET_TIMEOUT, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));

        // Fire it.
        VolleyQueue.getInstance().addToRequestQueue(request, tag);
}