static List<Message> process(List<Message> received) {
    // TODO: 按sequence去除重复消息    Set<Message> mess = new TreeSet<>(new Comparator<Message>() {
        @Override        public int compare(Message t0, Message t1) {
            return Integer.compare(t0.sequence, t1.sequence);
        }
    });
    mess.addAll(received);
    received = null;
    received = new ArrayList<>(mess);
    return received;
}