EventManager::getInstanceId

private function getInstanceId(string $masterId, Event $event): string
{
	$base = $masterId . '_';
	if ($event->isFullDayEvent())
	{
		return $base . $event->getOriginalDateFrom()->setTimezone(Util::prepareTimezone())->format('Ymd');
	}
	else
	{
		return $base . $event->getOriginalDateFrom()->setTimezone(Util::prepareTimezone())->format('YmdTHisZ');
	}
}