@VisibleForTesting
  public Int2IntMap collectProbeLengthsHistogram() {
    @SuppressWarnings("SSBasedInspection")
    Int2IntOpenHashMap histo = new Int2IntOpenHashMap();
    for (int i = 0; i < pages.length(); i++) {
      final PageImpl page = pages.get(i);
      if (page != null) {
        final int probingLength = probingSequenceLengthFor(pages, page.pageIndex());
        histo.mergeInt(probingLength, 1, Integer::sum);
      }
    }
    return histo;
  }
@VisibleForTesting
  public Int2IntMap collectProbeLengthsHistogram()