@VisibleForTesting
  static long chunkIdToOffset(long chunkId) {
    long offset = chunkIdToOffsetUnchecked(chunkId);
    if (!AlignmentUtils.is64bAligned(offset)) {
      throw new IllegalArgumentException("chunkId(=" + chunkId + ") is invalid: chunkOffsetInFile(=" + offset + ") is not 64b-aligned");
    }
    return offset;
  }
@VisibleForTesting
  static long chunkIdToOffset(long chunkId)