private function getCallbackClass()
    {
        // define callback class namespace/name full path
        $cName = (self::$Request->getCallbackAlias() ?? '\Apps\Controller\\' . env_name . '\\' . self::$Request->getController());
        if (!class_exists($cName)) {
            throw new NotFoundException('Callback class not found: ' . App::$Security->strip_tags($cName));
        }

        return new $cName;
    }