CS-D must have a clear error message if FactHandle is null

    @Override
    public void update(Object fact) {
        FactHandle factHandle = kieSession.getFactHandle(fact);
        kieSession.update(factHandle, fact);
     }

    private void update(Object entity, String variableName) {
        FactHandle factHandle = kieSession.getFactHandle(entity);
        if (factHandle == null) {
            throw new IllegalArgumentException("The entity (" + entity
                    + ") was never added to this ScoreDirector.\n"
                    + "Maybe that specific instance is not in the return values of the "
                    + PlanningSolution.class.getSimpleName() + "'s entity members ("
                    + getSolutionDescriptor().getEntityMemberAndEntityCollectionMemberNames() + ").");
        }
        kieSession.update(factHandle, entity, variableName);
    }

Caused by: java.lang.NullPointerException
    at org.drools.core.common.NamedEntryPoint.update(NamedEntryPoint.java:353)
    at org.drools.core.common.NamedEntryPoint.update(NamedEntryPoint.java:338)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.update(StatefulKnowledgeSessionImpl.java:1587)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.update(StatefulKnowledgeSessionImpl.java:1559)
    at org.optaplanner.core.impl.score.stream.drools.DroolsConstraintSession.update(DroolsConstraintSession.java:47)
    at org.optaplanner.core.impl.score.director.stream.ConstraintStreamScoreDirector.afterVariableChanged(ConstraintStreamScoreDirector.java:141)
    at org.optaplanner.core.impl.domain.variable.inverserelation.SingletonInverseVariableListener.retract(SingletonInverseVariableListener.java:96)
    at org.optaplanner.core.impl.domain.variable.inverserelation.SingletonInverseVariableListener.beforeVariableChanged(SingletonInverseVariableListener.java:46)
    at org.optaplanner.core.impl.domain.variable.listener.support.VariableListenerSupport.beforeVariableChanged(VariableListenerSupport.java:174)
    at org.optaplanner.core.impl.score.director.AbstractScoreDirector.beforeVariableChanged(AbstractScoreDirector.java:433)
    at org.optaplanner.core.impl.score.director.AbstractScoreDirector.changeVariableFacade(AbstractScoreDirector.java:446)
    at org.optaplanner.core.impl.heuristic.selector.move.generic.chained.ChainedChangeMove.doMoveOnGenuineVariables(ChainedChangeMove.java:74)
    at org.optaplanner.core.impl.heuristic.move.AbstractMove.doMove(AbstractMove.java:36)
    at org.optaplanner.core.impl.heuristic.move.AbstractMove.doMove(AbstractMove.java:31)
    at org.optaplanner.core.impl.score.director.AbstractScoreDirector.doAndProcessMove(AbstractScoreDirector.java:178)
    at org.optaplanner.core.impl.heuristic.thread.MoveThreadRunner.run(MoveThreadRunner.java:146)
    at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)