Save content without entering a PublishTime:
Catchable Fatal Error: Argument 1 passed to Integrated\Bundle\ContentBundle\Form\Type\PublishTimeType::Integrated\Bundle\ContentBundle\Form\Type{closure}() must be an instance of Integrated\Bundle\ContentBundle\Document\Content\Embedded\PublishTime, null given, called in /home/integratedfordevelopers/vendor/symfony/symfony/src/Symfony/Component/Validator/Constraints/CallbackValidator.php on line 54 and defined