/**
* Returns true if the response must be revalidated by caches.
*
* This method indicates that the response must not be served stale by a
* cache in any circumstance without first revalidating with the origin.
* When present, the TTL of the response should not be overridden to be
* greater than the value provided by the origin.
*
* @return bool true if the response must be revalidated by a cache, false otherwise
*
* @api
*/
public function mustRevalidate()
{
return parent::mustRevalidate();
}