code: private static void fillButtonSlot(CmsListItemWidget listItemWidget, int index, Widget widget, int[] slotMapping) {
  
          int realIndex = slotMapping[index];
          if (realIndex >= 0) {
              SimplePanel panel = (SimplePanel)listItemWidget.getButton(slotMapping[index]);
              panel.clear();
              panel.add(widget);
          }
      }
docs: Fills a slot for a button in a publish list item widget.<p>
  
  @param listItemWidget the list item widget
  @param index the slot index
  @param widget the widget which should be displayed in the slot
  @param slotMapping array mapping logical slot ids to button indexes