@Override
  public void onCompletion(AggregatedAccountStorageStats results, Exception exception) {
    if (exception != null) {
      logger.info(
          "Aggregator task encountered an exception but result is not null. Processing the result as aggregation is complete.");
    }
    accountService.selectInactiveContainersAndMarkInStore(results);
  }
When the aggregation report has been generated successfully, this method will be invoked and associated {@link AccountService}
will select container which valid data size equals to zero from DELETE_IN_PROGRESS {@link Container} set and mark it INACTIVE in zookeeper.
@param results the StatsSnapshot whose values represents aggregated stats across all partitions.
@param exception Exception occurred when updating Helix property store, not in aggregation phase, the result is still solid.
ambry-api/src/main/java/com/github/ambry/account/AccountServiceCallback.java