@Override
  public void close() {
    if (open.compareAndSet(true, false)) {
      maybeUnsubscribeChangeTopic();
      if (scheduler != null) {
        shutDownExecutorService(scheduler, config.updaterShutDownTimeoutMs, TimeUnit.MILLISECONDS);
      }
      helixStore.stop();
      if (notifier != null) {
        notifier.close();
      }
    }
  }
Helper function to update {@link Account} metadata.
@param accounts The {@link Account} metadata to update.
@param accountMetadataStore The {@link AccountMetadataStore}.
@throws AccountServiceException when the update operation fails.
ambry-account/src/main/java/com/github/ambry/account/HelixAccountService.java