change `WorkItem::serialize()` to create a new `LoggedParticipant` object only if the `ParticipantInterface` object is not instance of `LoggedParticipant`
change `WorkItem::serialize()` to create a new `LoggedParticipant` object only if the `ParticipantInterface` object is not instance of `LoggedParticipant`

phpmentors-jp/workflower