code: @Disconnect
      public void onDisconnect(AtmosphereResourceEvent event) {
          if (event.isCancelled()) {
              logger.info("Browser {} unexpectedly disconnected", event.getResource().uuid());
          } else if (event.isClosedByClient()) {
              logger.info("Browser {} closed the connection", event.getResource().uuid());
          }
      }
docs: Invoked when the client disconnect or when an unexpected closing of the underlying connection happens.
  
  @param event