code: public static <S extends Solution<?>> double[] getObjectiveArrayFromSolutionList(List<S> solutionList, int objective) {
      double[] result = new double[solutionList.size()];
  
      for (int i = 0; i < solutionList.size(); i++) {
        result[i] = solutionList.get(i).getObjective(objective);
      }
      return result;
    }
docs: Given a solution list and the identifier of an objective (0, 1, etc), returns an array with
  the values of that objective in all the solutions of the list
  
  @param solutionList
  @param objective
  @param <S>
  @return