docs: protected String getPathInfo(HttpServletRequest req) {
  
          String path = req.getPathInfo();
          if (path == null) {
              // if the HttpServletRequest#getPathInfo() method does not work properly
              String requestErrorPageAttribute = getSystemInfo().getServletContainerSettings().getRequestErrorPageAttribute();
              if (requestErrorPageAttribute != null) {
                  // use the proper page attribute
                  path = (String)req.getAttribute(requestErrorPageAttribute);
                  if (path != null) {
                      int pos = path.indexOf("/", 1);
                      if (pos > 0) {
                          // cut off the servlet name
                          path = path.substring(pos);
                      }
                  }
              }
          }
          if (path == null) {
              path = "/";
          }
          return path;
      }