OnTaskDeadLineChanged::getDateTimestamp

private function getDateTimestamp(?string $dateTime): ?int
{
	if (!$dateTime)
	{
		return null;
	}

	$timestamp = MakeTimeStamp($dateTime);

	if ($timestamp === false)
	{
		$timestamp = strtotime($dateTime);
		if ($timestamp !== false)
		{
			$timestamp += CTimeZone::GetOffset() - DateTime::createFromTimestamp($timestamp)->getSecondGmt();
		}
	}

	return $timestamp;
}