@Override
      public void customizeRenderer(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
        final Object o = ((DefaultMutableTreeNode)value).getUserObject();
        if (o instanceof Pair) {
          getTextRenderer().append((String)((Pair<?, ?>)o).second);
        }
      }
@Override
      public void customizeRenderer(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus)