@Override
    public int read(int fileId,
                    int defaultValue) throws IOException {
      if (defaultValue != 0) {
        throw new UnsupportedOperationException(
          "defaultValue=" + defaultValue + ": so far only 0 is supported default value for fast-attributes");
      }
      return helper.readIntField(fileId, FIELD_OFFSET);
    }
@Override
    public int read(int fileId,
                    int defaultValue)