docs: public List<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") ;
      } else if (solutionList.size() < numberOfSolutionsToBeReturned) {
        throw new JMetalException("The solution list size (" + solutionList.size() +") is less than "
            + "the number of requested solutions ("+numberOfSolutionsToBeReturned+")") ;
      }
  
      return SolutionListUtils.selectNRandomDifferentSolutions(numberOfSolutionsToBeReturned, solutionList) ;
    }