AIX + ibm jdk NPE

java.lang.NullPointerException: null
	at org.optaplanner.core.impl.domain.variable.listener.VariableListenerSupport.beforeVariableChanged(VariableListenerSupport.java:144)
	at org.optaplanner.core.impl.score.director.AbstractScoreDirector.beforeVariableChanged(AbstractScoreDirector.java:257)
	at org.optaplanner.core.impl.heuristic.selector.move.generic.ChangeMove.doMove(ChangeMove.java:66)
	at org.optaplanner.core.impl.constructionheuristic.decider.ConstructionHeuristicDecider.doMove(ConstructionHeuristicDecider.java:103)
	at org.optaplanner.core.impl.constructionheuristic.decider.ConstructionHeuristicDecider.decideNextStep(ConstructionHeuristicDecider.java:77)
	at org.optaplanner.core.impl.constructionheuristic.DefaultConstructionHeuristicPhase.solve(DefaultConstructionHeuristicPhase.java:67)
	at org.optaplanner.core.impl.solver.DefaultSolver.runPhases(DefaultSolver.java:213)
	at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:176)
	at org.optaplanner.examples.common.app.SolverPerformanceTest.solve(SolverPerformanceTest.java:79)
	at org.optaplanner.examples.common.app.SolverPerformanceTest.runSpeedTest(SolverPerformanceTest.java:63)
	at org.optaplanner.examples.common.app.SolverPerformanceTest.runSpeedTest(SolverPerformanceTest.java:58)
	at org.optaplanner.examples.pas.app.PatientAdmissionSchedulePerformanceTest.solveTestdata01(PatientAdmissionSchedulePerformanceTest.java:46)