private HashMapSegmentLayout allocateSegment(int hashSuffix,
                                               byte hashSuffixDepth) throws IOException {
    int segmentsCount = header.actualSegmentsCount();
    int segmentIndex = segmentsCount + 1;// segmentIndex starts with 1 (segmentIndex=0 is the header)

    HashMapSegmentLayout segment = new HashMapSegmentLayout(bufferSource, segmentIndex, header.segmentSize());
    segment.updateHashSuffix(hashSuffix, hashSuffixDepth);

    header.actualSegmentsCount(segmentsCount + 1);

    return segment;
  }
private HashMapSegmentLayout allocateSegment(int hashSuffix,
                                               byte hashSuffixDepth)