code: public static PageFlowStack get( HttpServletRequest request, ServletContext servletContext, boolean createIfNotExist )
      {
          StorageHandler sh = Handlers.get( servletContext ).getStorageHandler();
          HttpServletRequest unwrappedRequest = PageFlowUtils.unwrapMultipart( request );
          RequestContext rc = new RequestContext( unwrappedRequest, null );
          String attrName = ScopedServletUtils.getScopedSessionAttrName( JPF_STACK_ATTR, unwrappedRequest );
          PageFlowStack jpfStack = ( PageFlowStack ) sh.getAttribute( rc, attrName );
          
          if ( jpfStack == null && createIfNotExist )
          {
              jpfStack = new PageFlowStack( servletContext );
              jpfStack.save( request );
          }
          else if ( jpfStack != null )
          {
              jpfStack.setServletContext( servletContext );
          }
          
          return jpfStack;
      }
docs: Get the stack of nested page flows for the current user session.  Create and store an empty
  stack if none exists.
  
  @param request the current HttpServletRequest.
  @param servletContext the current ServletContext.
  @return a {@link PageFlowStack} of nested page flows ({@link PageFlowController}s) for the current user session.