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.
@api
Boolean true if the response must be revalidated by a cache, false otherwise
public function mustRevalidate() {
return $this->headers
->hasCacheControlDirective('must-revalidate') || $this->headers
->has('proxy-revalidate');
}