code: public static PageFlowController getPageFlow(ServletRequest request, ServletResponse response) {
          assert request instanceof HttpServletRequest;
  
          PageFlowController jpf = PageFlowUtils.getCurrentPageFlow((HttpServletRequest)request);
          if(jpf != null)
              return jpf;
          else {
              String message = "There is no current Page Flow!";
              LOGGER.error(message);
              throw new RuntimeException(message);
          }
      }
docs: Internal method!
  
  This method is used by the expression engine to get the current page flow.  If no page flow is
  found, an exception will be thrown.
  @param request the request
  @param response the response
  @return the page flow