public SortedSet<Integer> getWeeks() {
final ExecutionCourse executionCourse = shift.getExecutionCourse();
final YearMonthDay firstPossibleLessonDay = executionCourse.getMaxLessonsPeriod().getLeft();
final YearMonthDay lastPossibleLessonDay = executionCourse.getMaxLessonsPeriod().getRight();
return getWeeks(new Interval(firstPossibleLessonDay.toDateTimeAtMidnight(), lastPossibleLessonDay.toDateTimeAtMidnight()
.plusDays(1)));
}
public SortedSet<Integer> getWeeks(final Interval lessonInterval) {
final SortedSet<Integer> weeks = new TreeSet<Integer>();