lib/zookeeper.js
function writeTopicConfig(client, topic, configs, callback) {
  debug('writeTopicConfig: "%s", %j', topic, configs);
  updateEntityConfig(client, getTopicConfigPath(topic), configs, callback);
}
function writeTopicConfig(client, topic, configs, callback) {
  debug('writeTopicConfig: "%s", %j', topic, configs);
  updateEntityConfig(client, getTopicConfigPath(topic), configs, callback);
}
function writeTopicConfig ( client , topic , configs , callback ) { debug ( 'writeTopicConfig: "%s", %j' , topic , configs ) ; updateEntityConfig ( client , getTopicConfigPath ( topic ) , configs , callback ) ; }
Write out the topic config to zk, if there is any

@param {ZkClient} client
@param {String} topic
@param {Object} configs
@param {Function} callback
Write out the topic config to zk if there is any