code: @OnClose
      public void onClose(Session session, CloseReason closeReason)
      {
          logger.info("WebSocket closed. : SessionId={}, Reason={}", session.getId(),
                  closeReason.toString());
          AmLogServerAdapter.getInstance().onClose(session);
      }
docs: Websocket connection close.
  
  @param session session
  @param closeReason closeReason