func (m *muxServer) close() {
	m.cancel()
	m.recvMu.Lock()
	defer m.recvMu.Unlock()

	if m.inbound != nil {
		xioutil.SafeClose(m.inbound)
		m.inbound = nil
	}

	if m.outBlock != nil {
		xioutil.SafeClose(m.outBlock)
		m.outBlock = nil

	}

	if !m.checkSeq(seq) {
		return
	}
	if m.acked || m.outBlock == nil {
		return
	}
	available := cap(m.outBlock)
	for i := 0; i < available; i++ {
		m.outBlock <- struct{}{}
	}
	m.acked = true
}

func (m *muxClient) unblockSend(seq uint32) {
	if !m.checkSeq(seq) {
		return
	}
	select {
	case m.outBlock <- struct{}{}:
	default:

  /**
   * <a href="https://www.loc.gov/preservation/digital/formats/fdd/fdd000379.shtml">Microsoft
   * Outlook</a> items.
   *
   * @since 27.1
   */
  public static final MediaType MICROSOFT_OUTLOOK =
      createConstant(APPLICATION_TYPE, "vnd.ms-outlook");

  /**
   * <a