public function get_additional_login_parameters() {
        $params = '';
        if ($this->system) {
            if (!empty($this->issuer->get('loginparamsoffline'))) {
                $params = $this->issuer->get('loginparamsoffline');
            }
        } else {
            if (!empty($this->issuer->get('loginparams'))) {
                $params = $this->issuer->get('loginparams');
            }
        }
        if (empty($params)) {
            return [];
        }
        $result = [];
        parse_str($params, $result);
        return $result;
    }