is::getStartDatePlanGmt

public function getStartDatePlanGmt($getCreatedDateOnNull = false)
{
	$date = $this->getStartDateOrCreatedDate($getCreatedDateOnNull);

	if ((string)$date == '')
	{
		return null;
	}

	if ($this->startDatePlanGmt === null)
	{
		if ($date instanceof DateTime)
		{
			$date = $date->toString(); //toStringGmt
		}

		$this->startDatePlanGmt = DateTime::createFromUserTimeGmt($date); // string or object allowed here
	}

	return clone $this->startDatePlanGmt;
}