[TYPO3-mvc] Optional \DateTime Property

[Philipp Wrann]

Hey

How can i set a Property of type \DateTime optional?
I allways get a validation error because the property should be \DateTime but is NULL

I solved it that way:
if ($this->request->hasArgument('groupRequest')) {
				$request = $this->request->getArgument('groupRequest');
				if (strlen($request['alternateArrival'])) {
					$mappingConfiguration->forProperty('alternateArrival')->setTypeConverterOption(
						'TYPO3\\CMS\\Extbase\\Property\\TypeConverter\\DateTimeConverter',
						\TYPO3\CMS\Extbase\Property\TypeConverter\DateTimeConverter::CONFIGURATION_DATE_FORMAT,
						$this->settings['dateFormat']
					);
				} else {
					$mappingConfiguration->skipProperties('alternateArrival');
				}
				if (strlen($request['alternateDeparture'])) {
					$mappingConfiguration->forProperty('alternateDeparture')->setTypeConverterOption(
						'TYPO3\\CMS\\Extbase\\Property\\TypeConverter\\DateTimeConverter',
						\TYPO3\CMS\Extbase\Property\TypeConverter\DateTimeConverter::CONFIGURATION_DATE_FORMAT,
						$this->settings['dateFormat']
					);	
				} else {
					$mappingConfiguration->skipProperties('alternateDeparture');
				}	
			}

Can i set @optional or something in the property?
cant find documentations on this