} }
	    public void beforeAdd(Event event, Person person) {		if (event instanceof GratuityEvent) {		    final GratuityEvent gratuityEvent = (GratuityEvent) event;		    if (gratuityEvent.getStudentCurricularPlan().hasGratuityEvent(			    gratuityEvent.getExecutionYear())) {			throw new DomainException(				"error.accounting.events.gratuity..GratuityEvent.person.already.has.gratuity.event.for.student.curricular.plan.and.year");		    }		}	    }