@Override
 public String getAuthUrl() {
   QueryParams params =
       new QueryParams()
           .add("client_id", clientId)
           .add("redirect_uri", callbackUrl)
           .add("response_type", "code")
           .add("display", "touch")
           .add("scope", "likes+comments+relationships", false);
   return AUTH_URL + params.asUrlParams();
 }
 private String makeApiUrl(String path, QueryParams queryParams, Object... pathParams) {
   return API_URL + String.format(Locale.US, path, pathParams) + queryParams.asUrlParams();
 }