code: public RequestDispatcher getRequestDispatcher(String url)
      {
          if (url == null)
              return null;
  
          if (!url.startsWith("/"))
          {
              String relTo=URI.addPaths(_servletPath,_pathInfo);
              int slash=relTo.lastIndexOf("/");
              if (slash>1)
                  relTo=relTo.substring(0,slash+1);
              else
                  relTo="/";
              url=URI.addPaths(relTo,url);
          }
      
          return _servletHandler.getServletContext().getRequestDispatcher(url);
      }
docs: /* ------------------------------------------------------------