Created attachment 529782 [details]
Simple reproducer

Description of problem:
When using multithreaded evaluation I can't get query results.

Version-Release number of selected component (if applicable):
BRMS-5.2.0.GA

How reproducible:
Every time.

Steps to Reproduce:
1. Run the attached reproducer
  
Actual results:
*******************************************************************************************************
Partition task manager caught an unexpected exception: null
Drools is capturing the exception to avoid thread death. Please report stack trace to development team.
java.lang.NullPointerException
	at org.drools.base.org.drools.base.DroolsQuery783328245$getName.getValue(Unknown Source)
	at org.drools.base.ClassFieldReader.getValue(ClassFieldReader.java:86)
	at org.drools.base.evaluators.EqualityEvaluatorsDefinition$StringEqualEvaluator.evaluate(EqualityEvaluatorsDefinition.java:1881)
	at org.drools.rule.LiteralRestriction.isAllowed(LiteralRestriction.java:87)
	at org.drools.rule.LiteralConstraint.isAllowed(LiteralConstraint.java:109)
	at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:130)
	at org.drools.reteoo.PartitionTaskManager$FactAssertAction.execute(PartitionTaskManager.java:272)
	at org.drools.reteoo.PartitionTaskManager$PartitionTask.run(PartitionTaskManager.java:116)
	at org.drools.concurrent.ExternalExecutorService$ObservableRunnable.run(ExternalExecutorService.java:443)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:679)

Expected results:
Query results are retrieved and application ends correctly.

Additional info:
If you remove the rule "print event" from drl file, it all goes well. However if you remove the rule and fact inserting you get the same exception.