public Watch.Watcher watchKeyChanges(final String key, final Watch.Listener listener) {
        WatchOption option = WatchOption.newBuilder().isPrefix(true).build();

        return client.getWatchClient().watch(bytesOf(key), option, listener);
    }
watchKeyChanges.

@param key key
@param listener listener
@return {@link Watch.Watcher}
shenyu-registry/shenyu-registry-etcd/src/main/java/org/apache/shenyu/registry/etcd/EtcdClient.java