public void watchClose(final String key) {
        if (watchCache.containsKey(key)) {
            watchCache.get(key).close();
            watchCache.remove(key);
        }
        if (watchChildCache.containsKey(key)) {
            watchChildCache.get(key).close();
            watchChildCache.remove(key);
        }
    }
cancel subscribe.

@param key node name
shenyu-sync-data-center/shenyu-sync-data-etcd/src/main/java/org/apache/shenyu/sync/data/etcd/EtcdClient.java