code: protected void renderLabel(AbstractRenderAppender writer, TreeElement node)
      {
          String label = node.getLabel();
          if (label != null) {
              renderLabelPrefix(writer, node);
              if (_trs.escapeContent) {
                  HtmlUtils.filter(label, writer);
              }
              else {
                  writer.append(label);
              }
              renderLabelSuffix(writer, node);
          }
      }
docs: Render the label for this node (if any).
  @param writer the appender where the tree markup is appended
  @param node the node to render