code: @Override
      public void clear() {
          values.clear();
          listBox.clear();
  
          clearStatusText();
          if (emptyPlaceHolder != null) {
              insertEmptyPlaceHolder(emptyPlaceHolder);
          }
          reload();
          if (isAllowBlank()) {
              addBlankItemIfNeeded();
          }
      }
docs: Removes all items from the list box.