code: private void resizeNodeArrays(int newBucketCount)
      {
          // every per-bucket array needs to be updated
          counts.ensureCapacity(newBucketCount);
          valuePositions.ensureCapacity(newBucketCount);
          nextPointers.ensureCapacity(newBucketCount);
          valueAndGroupHashes.ensureCapacity(newBucketCount);
          groupIds.ensureCapacity(newBucketCount);
      }
docs: parallel arrays with data for