public static function csrfMetaTags(RequestApplicationInterface $app)
    {
        $encoding = $app->charset;
        if ($app->reqHelper->enableCsrfValidation) {
            return static::tag('meta', '', ['name' => 'csrf-param', 'content' => $app->reqHelper->csrfParam], $encoding) . "\n    "
                . static::tag('meta', '', ['name' => 'csrf-token', 'content' => $app->reqHelper->getCsrfToken()], $encoding) . "\n";
        }

        return '';
    }