Doctrine\ODM\MongoDB\UnitOfWork::cascadeDetach PHP Method

    private function cascadeDetach($document, array &$visited)
    {
        $class = $this->dm->getClassMetadata(get_class($document));
        foreach ($class->fieldMappings as $mapping) {
            if (!$mapping['isCascadeDetach']) {
                continue;
            }
            $relatedDocuments = $class->reflFields[$mapping['fieldName']]->getValue($document);
            if ($relatedDocuments instanceof Collection || is_array($relatedDocuments)) {
                if ($relatedDocuments instanceof PersistentCollectionInterface) {
                    // Unwrap so that foreach() does not initialize
                    $relatedDocuments = $relatedDocuments->unwrap();
                }
                foreach ($relatedDocuments as $relatedDocument) {
                    $this->doDetach($relatedDocument, $visited);
                }
            } elseif ($relatedDocuments !== null) {
                $this->doDetach($relatedDocuments, $visited);
            }
        }
    }