docs: public S execute(List<S> solutionList) {
      if (null == solutionList) {
        throw new JMetalException("The solution list is null") ;
      } else if (solutionList.isEmpty()) {
        throw new JMetalException("The solution list is empty") ;
      }
  
      int bestSolution = 0 ;
      for (int i = 1; i < solutionList.size(); i++) {
        if (comparator.compare(solutionList.get(i), solutionList.get(bestSolution)) < 0) {
          bestSolution = i;
        }
      }
  
      return solutionList.get(bestSolution) ;
    }