public Object provide(Object source, Object obj) {
final ManageEnrolmentsBean bean = (ManageEnrolmentsBean) source;
final List<ExecutionSemester> result = new ArrayList<ExecutionSemester>();
ExecutionSemester each = bean.getProcess().getExecutionYear().getFirstExecutionPeriod();
while (each != null) {
result.add(each);
each = each.getNextExecutionPeriod();
}
Collections.sort(result, new ReverseComparator(ExecutionSemester.COMPARATOR_BY_SEMESTER_AND_YEAR));
return result;