code: public void shutdown() {
          try {
              this.scheduler.shutdownNow();
          } catch (Exception ignored) {
          }
  
          for (final WaitingServer server : list) {
              try {
                  server.destroy();
                  log.info("[GatewayServerClear] Destroy gateway server {}", server);
              } catch (Exception ignored) {
              }
          }
          list.clear();
      }
docs: Shutdown.