private void markAsDeleted(MockId id) {
    deletedKeys.add(id);
    undeletedKeys.remove(id);
    liveKeys.remove(id);
  }
Marks {@code id} as deleted.
@param id the {@link MockId} to mark as deleted.
ambry-store/src/test/java/com/github/ambry/store/CuratedLogIndexState.java