[rules-users] NPE in Event.attribute.getIntValue()

Version: 5.5.0 Drools Expert + Fusion Stateful ksession in STREAM mode In an integration test, I ___sometimes_____!!! (always the same variables... ) get the following Exception: Exception in thread "Thread-1" java.lang.NullPointerException at org.drools.base.com.myApp.model.Measurement1965915394$getValue.getIntValue(Unknown Source) at org.drools.base.extractors.BaseIntClassFieldReader.getValue(BaseIntClassFieldReader.java:52) at org.drools.base.ClassFieldReader.getValue(ClassFieldReader.java:87) at org.drools.rule.Declaration.getValue(Declaration.java:233) at org.drools.base.mvel.MVELCompilationUnit.updateFactory(MVELCompilationUnit.java:362) at org.drools.base.mvel.MVELCompilationUnit.updateFactory(MVELCompilationUnit.java:289) at org.drools.rule.constraint.MvelConditionEvaluator.evaluate(MvelConditionEvaluator.java:59) at org.drools.rule.constraint.MvelConditionEvaluator.ensureBranchEvaluation(MvelConditionEvaluator.java:117) at org.drools.rule.constraint.MvelConditionEvaluator.ensureCompleteEvaluation(MvelConditionEvaluator.java:101) at org.drools.rule.constraint.MvelConditionEvaluator.ensureBranchEvaluation(MvelConditionEvaluator.java:120) at org.drools.rule.constraint.MvelConditionEvaluator.ensureCompleteEvaluation(MvelConditionEvaluator.java:101) at org.drools.rule.constraint.MvelConditionEvaluator.ensureCompleteEvaluation(MvelConditionEvaluator.java:90) at org.drools.rule.constraint.MvelConditionEvaluator.getAnalyzedCondition(MvelConditionEvaluator.java:82) at org.drools.rule.constraint.MvelConstraint.executeJitting(MvelConstraint.java:270) at org.drools.rule.constraint.MvelConstraint.access$200(MvelConstraint.java:51) at org.drools.rule.constraint.MvelConstraint$ConditionJitter.run(MvelConstraint.java:250) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) at java.lang.Thread.run(Thread.java:695) Where Measurement is one of my custom model classes and an @event. I tried to catch the exception but I don't know where it actually occurs. There is one rule that retracts Measurement in certain situations - the problem might be related to that (is it unwise to retract @event ?). Any idea? - Alex