@Override
  public synchronized void updateDatasetVersionState (String accountName, String containerName, String datasetName,
      String version, DatasetVersionState datasetVersionState) {
    //no-op
  }
Constructor.
@param shouldReturnOnlyUnknown {@code true} if always returns {@link InMemAccountService#UNKNOWN_ACCOUNT} when queried
                                                    by account name; {@code false} to do the actual query.
@param notifyConsumers {@code true} if consumers should be notified of account changes. {@code false} otherwise.
ambry-test-utils/src/main/java/com/github/ambry/account/InMemAccountService.java