code: @Handler(channels = NetworkChannel.class)
      public void onPurge(Purge event, IOSubchannel netChannel) {
          LinkedIOSubchannel.downstreamChannel(this, netChannel,
              WebAppMsgChannel.class).ifPresent(appChannel -> {
                  appChannel.handlePurge(event);
              });
      }
docs: Forwards a {@link Purge} event to the application channel.
  
  @param event the event
  @param netChannel the net channel