code: protected void renderContent(AbstractRenderAppender writer, TreeElement node)
      {
          String ctnt = node.getContent();
          if (ctnt != null) {
              renderContentPrefix(writer, node);
              if (_trs.escapeContent) {
                  HtmlUtils.filter(ctnt, writer);
              }
              else {
                  writer.append(ctnt);
              }
              renderContentSuffix(writer, node);
          }
      }
docs: Render the Content for this node (if any).
  @param writer the appender where the tree markup is appended
  @param node the node to render