public ConsumerEvent peek(String consumerId) {
        String group =
                consumerHolder.getGroupName(consumerId);
        if (group != null) {
            ConcurrentHashMap<String, LinkedList<ConsumerEvent>> currentEventMap =
                    hasDisconnectEvent(group)
                            ? disconnectEventMap
                            : connectEventMap;
            LinkedList<ConsumerEvent> eventList =
                    currentEventMap.get(consumerId);
            if (eventList != null) {
                synchronized (eventList) {
                    return eventList.peek();
                }
            }
        } else {
            logger.warn(new StringBuilder(512)
                    .append("No group by consumer ")
                    .append(consumerId).toString());
        }
        return null;
    }
Peek a consumer event from event map,
disconnect event have priority over connect event

@param consumerId the consumer id
@return the head of event list, or null if event list is empty
inlong-tubemq/tubemq-server/src/main/java/org/apache/inlong/tubemq/server/master/nodemanage/nodeconsumer/ConsumerEventManager.java