docs: private void createMaintenanceTimeZoneControl() {
          // ComboBoxBuilder cannot be used here, because Builder do
          // 'comboBox.setItemCaptionPropertyId(SPUILabelDefinitions.VAR_NAME);'
          // which interferes our code: 'timeZone.addItems(getAllTimeZones());'
          timeZone = new ComboBox();
          timeZone.setId(UIComponentIdProvider.MAINTENANCE_WINDOW_TIME_ZONE_ID);
          timeZone.setCaption(i18n.getMessage("caption.maintenancewindow.timezone"));
          timeZone.addItems(getAllTimeZones());
          timeZone.setValue(getClientTimeZone());
          timeZone.addStyleName(ValoTheme.COMBOBOX_SMALL);
          timeZone.setTextInputAllowed(false);
          timeZone.setNullSelectionAllowed(false);
      }