code: func (mp *LogMergePolicy) sizeBytes(info *SegmentCommitInfo, w *IndexWriter) (n int64, err error) {
  	if mp.calibrateSizeByDeletes {
  		return mp.MergePolicyImpl.Size(info, w)
  	}
  	return info.SizeInBytes()
  }
docs: /*
  Return the byte size of the provided SegmentCommitInfo, pro-rated
  by percentage of non-deleted documents if SetCalibratedSizeByDeletes()
  is set.
  */