static List<Message> process(List<Message> received) {        // TODO: 按sequence去除重复消息        HashSet<Integer> sequenceSet = new HashSet<>();  // 使用hashset存储sequence        List<Message> newreceived = new ArrayList<>();   // 添加sequence对应的消息        for (Message message : received){  //检查消息            if (!sequenceSet.contains(message.sequence)) {                newreceived.add(message);                sequenceSet.add(message.sequence);            }        }        return newreceived;    }}