docs: public int doStartTag() throws JspException {
          //checkEnclosedInIncludeTag(); // Moved to TagLibValidator
  
          // Get request
          HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
  
          // Get filename
          subpage = createFileNameFromRequest(request);
  
          // Get include tag, and add to parameters
          IncludeTag includeTag = (IncludeTag) getParent();
          includeTag.addParameter(parameterName, new Oparam(subpage.getName()));
  
          // if ! subpage.exist || jsp newer than subpage, write new
          File jsp = new File(pageContext.getServletContext().getRealPath(request.getServletPath()));
  
          if (!subpage.exists() || jsp.lastModified() > subpage.lastModified()) {
              return EVAL_BODY_BUFFERED;
          }
  
          // No need to evaluate body again!
          return SKIP_BODY;
      }