public static function returnUrl()
    {
        if (self::$returnUrl === null) {
            $url = ['/' . ltrim(Yii::$app->requestedRoute, '/')];
            foreach (Yii::$app->request->queryParams as $key => $value) {
                $url[$key] = $value;
            }
            self::$returnUrl = Url::to($url);

        }
        return self::$returnUrl;
    }