public UsersTracker start() throws IOException {
LOG.debug("Starting table user tracker for path {}.", mUsersDir);
final CountDownLatch initializationLatch = new CountDownLatch(1);
mCache.getListenable().addListener(
new PathChildrenCacheListener() {
@Override
public void childEvent(CuratorFramework client, PathChildrenCacheEvent event)
throws Exception {
LOG.debug("Users tracker event received for path {}: {}.", mUsersDir, event);
switch (event.getType()) {