protected function getScheme($secured = null)
    {
        if (is_null($secured)) {
            if (is_null($this->cacheScheme)) {
                $this->cacheScheme = request('REQUEST_SCHEME', 'http', 'server').'://';

                return $this->cacheScheme;
            } else {
                $this->cacheScheme;
            }
        }

        return $secured ? 'http://' : 'https://';
    }