Neos\Neos\EventLog\Domain\Model\Event::addChildEvent PHP Method

    public function addChildEvent(Event $childEvent)
    {
        $this->childEvents->add($childEvent);
    }

 /**
  * Create a new event
  *
  * @param string $eventType
  * @param array $data
  * @param string $user
  * @param Event $parentEvent
  */
 public function __construct($eventType, $data, $user = null, Event $parentEvent = null)
 {
     $this->timestamp = new \DateTime();
     $this->eventType = $eventType;
     $this->data = $data;
     $this->accountIdentifier = $user;
     $this->parentEvent = $parentEvent;
     $this->childEvents = new ArrayCollection();
     if ($this->parentEvent !== null) {
         $parentEvent->addChildEvent($this);
     }
 }