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java.lang.NullPointerException: 	at java.util.concurrent.ConcurrentHashMap.hash(ConcurrentHashMap.java:333)	at java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1125)	at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:613)	at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:575)	at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirectorFactory.newKieSession(DroolsScoreDirectorFactory.java:113)	at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.resetKieSession(DroolsScoreDirector.java:68)	at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.setWorkingSolution(DroolsScoreDirector.java:61)	at org.optaplanner.core.impl.solver.scope.DefaultSolverScope.setWorkingSolutionFromBestSolution(DefaultSolverScope.java:198)	at org.optaplanner.core.impl.solver.DefaultSolver.solvingStarted(DefaultSolver.java:196)	at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:175)	at org.kie.server.services.optaplanner.SolverServiceBase$1.run(SolverServiceBase.java:329)	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)	at java.lang.Thread.run(Thread.java:745)