Created attachment 1138610 [details]
Exception stacktrace

Description of problem:

When serializing a persistent KieSession containing rule such as:

rule "Forall2"
when
  forall ( $pet : Pet ( owner.name == 'dog lady')
	  	  Pet ( this == $pet, type == Pet.PetType.dog )
	 )
then
end

with the fact:

  new Pet(Pet.PetType.dog, new Person("cat lady")) // the person name does not match the rule

then the following NPE is thrown during transaction commit (see the attachment for full stacktrace):

java.lang.NullPointerException: null
	at org.drools.core.marshalling.impl.ProtobufOutputMarshaller.writeRIANodeMemory(ProtobufOutputMarshaller.java:462) ~[drools-core-6.4.0.Beta2-redhat-1.jar:6.4.0.Beta2-redhat-1]
	at org.drools.core.marshalling.impl.ProtobufOutputMarshaller.writeNodeMemories(ProtobufOutputMarshaller.java:378) ~[drools-core-6.4.0.Beta2-redhat-1.jar:6.4.0.Beta2-redhat-1]
	at org.drools.core.marshalling.impl.ProtobufOutputMarshaller.serializeSession(ProtobufOutputMarshaller.java:166) ~[drools-core-6.4.0.Beta2-redhat-1.jar:6.4.0.Beta2-redhat-1]
...

This is a regression from 6.2.x, proposing as a blocker.

Version-Release number of selected component (if applicable):
BRMS 6.3.0.ER1

How reproducible:
always

Steps to Reproduce:
1. run unit test PersistentSessionForallTest from the PR (to be submitted)

Actual results:
NPE is thrown.

Expected results:
Test passes.