docs: private int findValueIndicesIndexForSubColumn()
    {
      final DimensionSelector keySelector = getKeySelector();
      final DimensionSelector valueSelector = getValueSelector();
  
      final IndexedInts keyIndices = keySelector.getRow();
      final IndexedInts valueIndices = valueSelector.getRow();
  
      final int limit = Math.min(keyIndices.size(), valueIndices.size());
  
      return IntStream
          .range(0, limit)
          .filter(i -> subColumnName.equals(keySelector.lookupName(keyIndices.get(i)))) // subColumnName is never null
          .findAny()
          .orElse(-1);
    }