code: public void setWeekDays(SortedSet<WeekDay> weekDays) {
  
          final SortedSet<WeekDay> newWeekDays = null == weekDays ? new TreeSet<WeekDay>() : weekDays;
          SortedSet<WeekDay> currentWeekDays = m_model.getWeekDays();
          if (!currentWeekDays.equals(newWeekDays)) {
              conditionallyRemoveExceptionsOnChange(new Command() {
  
                  public void execute() {
  
                      m_model.setWeekDays(newWeekDays);
                      onValueChange();
                  }
              }, !newWeekDays.containsAll(m_model.getWeekDays()));
          }
      }
docs: Set the weekdays at which the event should take place.
  @param weekDays the weekdays at which the event should take place.