code: private LocalDate zGetParentSelectedDate() {
          if (!hasParent()) {
              return null;
          }
          boolean useDatePicker = (parentDatePicker != null);
          return (useDatePicker) ? parentDatePicker.getDate() : parentCalendarPanel.getSelectedDate();
      }
docs: zGetParentSelectedDate, Returns the currently selected date from the parent DatePicker or
  parent independent CalendarPanel (using whichever parent currently exists). If this settings
  instance does not have a parent, then this will return null. Note that any calling code
  should generally verify whether or not this settings instance has a parent, before calling
  this function.