public String get(final String key) {
        List<KeyValue> keyValues = null;
        try {
            keyValues = client.getKVClient().get(bytesOf(key)).get().getKvs();
        } catch (InterruptedException | ExecutionException e) {
            LOG.error("get key error, key:{}", key, e);
        }

        if (CollectionUtils.isEmpty(keyValues)) {
            LOG.warn("get key {} is empty", key);
            return null;
        }
        return keyValues.iterator().next().getValue().toString(UTF_8);
    }
get node value.

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