java - Optaplanner :Error when displaying constraints scores -

I use the OTAPA Planner to optimize a vehicle routing extension. I have received rigorous and soft scores, but when I try to display obstacles, I receive this message:

  Exceptions in threads, "ADT-EventQQ-0" java.lang NullPointerException at org.optaplanner .core.impl.score.director.drools.DroolsScoreDirector.getConstraintMatchTotals (orD.O.P. >  
 The error line can be:  kieSession.fireAllRules ();  
 

You probably have entered the director. Forgot to call solution (s) . See the "explain the scores" section in Docs. In the reply of Okanela, the cessation becomes empty because of this.