[GSS](6.3.z)Setting the planning variable nullable in nurserostering examples causes NPE

+++ This bug was initially created as a clone of Bug #1329092 +++

Description of problem:
Platform issue for https://issues.jboss.org/browse/PLANNER-488

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
See steps listed in JIRA

Actual results:
NPE during the solver execution

Expected results:
Solve runs without exception

Additional info:

— Additional comment from JBoss Product and Program Management on 2016-04-21 04:10:19 EDT —

Since this issue was entered in Red Hat Bugzilla, the release flag has been
set to ? to ensure that it is properly evaluated for this release.

— Additional comment from Geoffrey De Smet on 2016-04-27 07:57:18 EDT —

Jiri Locker (QA) has isolated a reproducer (from a few billion to a few dozen calls).
Mario has just reproduced on an even smaller case in drools proper.
Once he fixes it, we 'll want permission to backport this urgent fix.

— Additional comment from John Skeoch on 2016-04-28 01:09:12 EDT —

User jvahala@redhat.com's account has been closed

— Additional comment from JBoss Product and Program Management on 2016-04-29 08:10:18 EDT —

Since this issue was entered in Red Hat Bugzilla, the release flag has been
set to ? to ensure that it is properly evaluated for this release.

— Additional comment from JBoss JIRA Server on 2016-05-02 09:35:06 EDT —

Mario Fusco <mario.fusco@gmail.com> updated the status of jira PLANNER-488 to Resolved

— Additional comment from Mario Fusco on 2016-05-02 10:22:40 EDT —

Fixed on master by https://github.com/droolsjbpm/drools/commit/11c04ff34