code: void updatePARTICIPANTS(
  		Set<? extends InteractionParticipant> oldSet,
  		Set<? extends InteractionParticipant> newSet)
  	{
  		if (oldSet != null)
  		{
  			PARTICIPANTS.removeComposited(oldSet);
  			for (InteractionParticipant ip : oldSet)
  			{
  				setParticipantInverse(ip, true);
  			}
  		}
  		if (newSet != null)
  		{
  			PARTICIPANTS.addComposited(newSet);
  			for (InteractionParticipant ip : newSet)
  			{
  				setParticipantInverse(ip, false);
  			}
  		}
  	}
docs: --------------------- ACCESORS and MUTATORS---------------------