code: function writeClientConfig(client, clientId, configs, callback) {
    debug('writeClientConfig: "%s", %j', clientId, configs);
    updateEntityConfig(client, getClientConfigPath(clientId), configs, callback);
  }
docs: Write out the client config to zk, if there is any
  
  @param {ZkClient} client
  @param {String} clientId
  @param {Object} configs
  @param {Function} callback