if (executionCourses == null || executionPeriod != executionCourses.iterator().next().getExecutionPeriod()) {
if (executionCourses == null || (!executionCourses.isEmpty() && executionPeriod != executionCourses.iterator().next().getExecutionPeriod())) {
	public Collection<ExecutionCourse> getExecutionCourses() throws FenixFilterException, FenixServiceException {		final ExecutionPeriod executionPeriod = getExecutionPeriod();		if (executionCourses == null || executionPeriod != executionCourses.iterator().next().getExecutionPeriod()) {	        final Student student = getStudent();	        executionCourses = new TreeSet<ExecutionCourse>(executionCourseComparator);	        for (final Attends attends : student.getAssociatedAttends()) {	        	final ExecutionCourse executionCourse = attends.getDisciplinaExecucao();	        	if (executionCourse.getExecutionPeriod() == executionPeriod) {	        		executionCourses.add(executionCourse);	        	}	        }		}        return executionCourses;	}