Neos\Flow\Persistence\PersistenceManagerInterface::persistAll PHP Method

    public function persistAll($onlyWhitelistedObjects = false);

 /**
  * Fetches the identifier from the set content object. If that
  * is not using automatically introduced UUIDs by Flow it tries
  * to call persistAll() and fetch the identifier again. If it still
  * fails, an exception is thrown.
  *
  * @return void
  * @throws IllegalObjectTypeException
  */
 protected function initializeObject()
 {
     if ($this->contentObject !== null) {
         $this->targetType = get_class($this->contentObject);
         $this->targetId = $this->persistenceManager->getIdentifierByObject($this->contentObject);
         if ($this->targetId === null) {
             $this->persistenceManager->persistAll();
             $this->targetId = $this->persistenceManager->getIdentifierByObject($this->contentObject);
             if ($this->targetId === null) {
                 throw new IllegalObjectTypeException('You cannot add an object without an identifier to a ContentObjectProxy. Probably you didn\'t add a valid entity?', 1303859434);
             }
         }
     }
 }