Neos\Flow\Persistence\Generic\Backend\AbstractBackend::removeDeletedReference PHP Method

    protected function removeDeletedReference($object, $propertyName, $propertyMetaData)
    {
        $previousValue = $this->persistenceSession->getCleanStateOfProperty($object, $propertyName);
        if ($previousValue !== null && is_array($previousValue) && isset($previousValue['value']['identifier']) && $this->reflectionService->getClassSchema($propertyMetaData['type'])->getModelType() === ClassSchema::MODELTYPE_ENTITY && $this->reflectionService->getClassSchema($propertyMetaData['type'])->isAggregateRoot() === false) {
            $object = $this->persistenceSession->getObjectByIdentifier($previousValue['value']['identifier']);
            if (!$this->visitedDuringPersistence->contains($object)) {
                $this->removeEntity($object);
            }
        }
    }