docs: public int doStartTag() throws JspException {
          try {
              if (parameterExists()) {
                  if (parameterValue instanceof JspFragment) {
                      // OPARAM or PARAM
                      ((JspFragment) parameterValue).service(pageContext);
                      /*
                      log("Service subpage " + pageContext.getServletContext().getRealPath(((Oparam) parameterValue).getName()));
  
                      pageContext.include(((Oparam) parameterValue).getName());
                      */
                  }
                  else {
                      // Normal JSP parameter value
                      JspWriter writer = pageContext.getOut();
                      writer.print(parameterValue);
                  }
  
                  return SKIP_BODY;
              }
              else {
                  return EVAL_BODY_INCLUDE;
              }
          }
          catch (ServletException se) {
              log(se.getMessage(), se);
              throw new JspException(se);
          }
          catch (IOException ioe) {
              String msg = "Caught an IOException in ValueOfTag.doStartTag()\n"
                      + ioe.toString();
              log(msg, ioe);
              throw new JspException(msg);
          }
      }