code: public PushedPageFlow pop( HttpServletRequest request )
      {
          PushedPageFlow ppf = ( PushedPageFlow ) _stack.pop();
          PageFlowController pfc = ppf.getPageFlow();
          pfc.setIsOnNestingStack( false );
          
          if ( request != null )  // may be null if we're called from valueUnbound()
          {
              ServletContext servletContext = getServletContext();
              
              // Reinitialize the page flow, in case it's lost its transient state.
              pfc.reinitialize( request, null, servletContext );
              ensureFailover( request, servletContext );   // to ensure that this attribute is replicated for session failover
          }
          
          return ppf;
      }
docs: Pop the most recently-pushed page flow from the stack of nested page flows in the session.
  
  @param request the current HttpServletRequest.
  @return a {@link PushedPageFlow} that represents the popped page flow.