private function buildOobLink($param, $action) {
    $code = $this->rpcHelper->getOobCode($param);
    $separator = parse_url($this->widgetUrl, PHP_URL_QUERY) ? '&' : '?';
    return $this->widgetUrl . $separator  .
        http_build_query(array('mode' => $action, 'oobCode' => $code));
  }