public function scheduleCollectionDeletion(PersistentCollectionInterface $coll) : void
    {
        $oid = spl_object_hash($coll);
        unset($this->collectionUpdates[$oid]);
        if (isset($this->collectionDeletions[$oid])) {
            return;
        }

        $this->collectionDeletions[$oid] = $coll;
        $this->scheduleCollectionOwner($coll);
    }