code: @Override
      public void shutdown() {
          synchronized (connections) {
              parent.channelCloses(this);
              for (final MessageInbound connection : connections) {
                  try {
                      connection.getWsOutbound().close(0, null);
                  } catch (final IOException e) {
                      LOG.error("Connection [" + connection.toString() + "] can't be closed.", e);
                  } finally {
                      final ExecutorService executorService = connectionThreads.get(connection);
                      if (executorService != null) {
                          executorService.shutdown();
                      }
                      connectionThreads.remove(connection);
                  }
              }
              connections.clear();
          }
          callback = null;
      }
docs: Disconnects all clients and makes the servlet refuse new connections.