protected function processQueryString($url)
    {
        $queryDataKeys = array_intersect($this->config->getRedirectableGetParams(), array_keys($_GET));
        $queryData     = array_intersect_key($_GET, array_flip($queryDataKeys));

        $connector = preg_match('/\?/', $url)
            ? "&"
            : "?";

        return count($queryData)
            ? $connector . http_build_query($queryData)
            : "";
    }