Cake\Network\Response::notModified PHP Method

    public function notModified()
    {
        $this->statusCode(304);
        $this->body('');
        $remove = ['Allow', 'Content-Encoding', 'Content-Language', 'Content-Length', 'Content-MD5', 'Content-Type', 'Last-Modified'];
        foreach ($remove as $header) {
            unset($this->_headers[$header]);
        }
    }