public function setAsNotModified()
{
$this->setStatusCode(304);
$this->setContent('');
// remove headers that MUST NOT be included with 304 Not Modified responses
$headersToRemove = ['Allow', 'Content-Encoding', 'Content-Language', 'Content-Length', 'Content-MD5', 'Content-Type', 'Last-Modified'];
foreach ($headersToRemove as $header) {
$this->headers->removeKey($header);
}
return $this;
}