docs: ReservoirLongsSketch downsampledCopy(final int maxK) {
      final ReservoirLongsSketch rls = new ReservoirLongsSketch(maxK, rf_);
      for (final long l: getSamples()) {
        // Pretending old implicit weights are all 1. Not true in general, but they're all
        // equal so update should work properly as long as we update itemsSeen_ at the end.
        rls.update(l);
      }
  
      // need to adjust number seen to get correct new implicit weights
      if (rls.getN() < itemsSeen_) {
        rls.forceIncrementItemsSeen(itemsSeen_ - rls.getN());
      }
  
      return rls;
    }