code: @Override
      public Score calculateScore() {
          variableListenerSupport.assertNotificationQueuesAreEmpty();
          Score score = easyScoreCalculator.calculateScore(workingSolution);
          if (score == null) {
              throw new IllegalStateException("The easyScoreCalculator (" + easyScoreCalculator.getClass()
                      + ") must return a non-null score (" + score + ") in the method calculateScore().");
          }
          if (workingInitScore != 0) {
              score = score.withInitScore(workingInitScore);
          }
          setCalculatedScore(score);
          return score;
      }
docs: ************************************************************************