It works in 6.3.3 or earlier version. For 6.3.4+ it does not work anymore.

In attach, there are 2 files:

1 drl rule file
1 bpmn2 process file

If you set the global itsNull to true, then it works in 6.3.4+
kcontext.getKieRuntime().setGlobal("itsNull", true);

Part of stacktrace error message for 6.3.4+ or letting the global boolean to null:
Caused by: java.lang.NullPointerException
at com.sasktel.osf.testjpbm.Rule_rule_two2072371598.eval0(Rule_rule_two2072371598.java:8)
at com.sasktel.osf.testjpbm.Rule_rule_two2072371598Eval0InvokerGenerated.evaluate(Unknown Source)
at com.sasktel.osf.testjpbm.Rule_rule_two2072371598Eval0Invoker.evaluate(Unknown Source)
at org.drools.core.rule.EvalCondition.isAllowed(EvalCondition.java:118) [drools-core-6.5.0.Final-redhat-2.jar:6.5.0.Final-redhat-2]

The result of 6.3.3 or setting the global boolean to true:
11:43:43,251 INFO [stdout] (http-127.0.0.1:8080-4) rule one:the string