AttachmentEditManager::getUid

public function getUid(): ?string
{
	if ($this->uid)
	{
		return $this->uid;
	}

	if ($this->event['ID'])
	{
		$eventFromDb = EventTable::getById($this->event['ID'])->fetch();

		if ($eventFromDb && $eventFromDb['DAV_XML_ID'] && $eventFromDb['DELETED'] === 'N')
		{
			$this->uid = $eventFromDb['DAV_XML_ID'];

			return $this->uid;
		}
	}

	return null;
}