@VisibleForTesting
  static long chunkOffsetToId(long chunkOffsetInFile) {
    AlignmentUtils.assert64bAligned(chunkOffsetInFile, "chunkOffsetInFile");

    //Since chunk offsets are 64b-aligned, we could drop 3 lowest bits from an offset while converting it to the id
    // => this way we could address wider offsets range with smaller ids

    //0 is considered invalid id (NULL_ID) everywhere in our code, so '+1' for first id to be 1
    return ((chunkOffsetInFile - FileHeader.HEADER_SIZE) >> 3) + 1;
  }
@VisibleForTesting
  static long chunkOffsetToId(long chunkOffsetInFile)