// requests on this server have completed.
func (s *Server) Close() {
	s.mu.Lock()
	if !s.closed {
		s.closed = true
		s.Listener.Close()
		s.Config.SetKeepAlivesEnabled(false)
		for c, st := range s.conns {
			// Force-close any idle connections (those between
			// requests) and new connections (those which connected
			// but never sent a request). StateNew connections are