List<LoginPeriod> loginPeriods = login.getLoginPeriods();
Set<LoginPeriod> loginPeriods = new TreeSet<LoginPeriod>(LoginPeriod.COMPARATOR_BY_BEGIN_DATE); loginPeriods.addAll(login.getLoginPeriods());
    public List<LoginPeriod> getLoginPeriodsWithoutInvitationPeriods() {	Person person = getUser().getPerson();	Login login = person.getLoginIdentification();	List<LoginPeriod> loginPeriods = login.getLoginPeriods();	for (Invitation invitation : person.getInvitationsOrderByDate()) {	    LoginPeriod period = login.readLoginPeriodByTimeInterval(invitation.getBeginDate(),		    invitation.getEndDate());	    if (period != null) {		loginPeriods.remove(period);	    }	}	return loginPeriods;    }