code: private void zSetParentSelectedDate(LocalDate dateValue) {
          if (parentDatePicker != null) {
              parentDatePicker.setDate(dateValue);
          }
          if (parentCalendarPanel != null) {
              parentCalendarPanel.setSelectedDate(dateValue);
          }
      }
docs: zSetParentSelectedDate, Sets the currently selected date for the parent DatePicker or parent
  independent CalendarPanel (using whichever parent currently exists). If this settings
  instance does not have a parent, then this will not do anything. Note that any calling code
  should generally verify whether or not this settings instance has a parent, before calling
  this function.