docs: @Override
    public List<List<DoubleSolution>> subsetGeneration() {
      List<List<DoubleSolution>> solutionGroupsList ;
  
      solutionGroupsList = generatePairsFromSolutionList(referenceSet1) ;
  
      solutionGroupsList.addAll(generatePairsFromSolutionList(referenceSet2));
  
      return solutionGroupsList ;
    }