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java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.hash(ConcurrentHashMap.java:333)[rt.jar:1.7.0_80] at java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1125)[rt.jar:1.7.0_80] at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:613)[drools-compiler-6.4.0.Final.jar:6.4.0.Final] at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:575)[drools-compiler-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirectorFactory.newKieSession(DroolsScoreDirectorFactory.java:113)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.resetKieSession(DroolsScoreDirector.java:68)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.score.director.drools.DroolsScoreDirector.setWorkingSolution(DroolsScoreDirector.java:61)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.solver.scope.DefaultSolverScope.setWorkingSolutionFromBestSolution(DefaultSolverScope.java:198)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.solver.DefaultSolver.solvingStarted(DefaultSolver.java:196)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.optaplanner.core.impl.solver.DefaultSolver.solve(DefaultSolver.java:175)[optaplanner-core-6.4.0.Final.jar:6.4.0.Final] at org.kie.server.services.optaplanner.SolverServiceBase$1.run(SolverServiceBase.java:329)[kie-server-services-optaplanner-6.4.0.Final.jar:6.4.0.Final] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[rt.jar:1.7.0_80] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[rt.jar:1.7.0_80] at java.lang.Thread.run(Thread.java:745)[rt.jar:1.7.0_80]