InstanceMap::add

public function add($item, $key = null): self
{
	/** @var SyncEvent $item */
	if ($key === null)
	{
		if ($date = $item->getEvent()->getOriginalDateFrom())
		{
			$key = self::getKeyByDate($date);
		}
		else
		{
			$key = self::getKeyByDate($item->getEvent()->getStart());
		}
	}

	parent::add($item, $key);

	return $this;
}