/**
  * @param HydrateEvent $event
  */
 public function handleHydrate(HydrateEvent $event)
 {
     $document = $event->getDocument();
     if (!$document instanceof ChildrenBehavior) {
         return;
     }
     $accessor = $event->getAccessor();
     $accessor->set('children', $this->proxyFactory->createChildrenCollection($document, $event->getOptions()));
 }