public function postSetData(FormEvent $event)
    {
        $collection = $event->getData();
        $form = $event->getForm();
        
        if ($collection instanceof PersistentCollection){
            
            foreach ($collection as $key => $image){
                if ($image instanceof MultiImageInterface && null !== $image->getId()){
                    try{
                        $this->imageManager->copyImagesToTemporaryDirectory($image);
                    } catch(\Gaufrette\Exception\FileNotFound $e){
                        $form->remove($key);
                        $collection->removeElement($image);
                    }
                    
                }
            }
        }
    }