Unmarshalling a marshalled session fails when using a newly initialized knowledgebase

A marshalled ReteooStatefulSession can not be unmarshalled if it contains an InitialFactHandle node and if the knowledge base has been reinitialized.

This bug started appearing because of this change:
https://github.com/droolsjbpm/drools/commit/0a3575e8073f2abc035b13e11381464e5ac17306#diff-4

-    public static final ClassObjectType InitialFact_ObjectType = new ClassObjectType( InitialFact.class );
+    public static final ClassObjectType InitialFact_ObjectType = new ClassObjectType( InitialFactImpl.class );

As far as I can tell, the above change caused the following:

1. The OutputMarshaller now marshalls the InitialFactnode: the following line now returns a non-null object, which causes the subsequent if clause to run (which wasn't happening before).

Approximately here:

• https://github.com/droolsjbpm/drools/blob/master/drools-core/src/main/java/org/drools/marshalling/impl/OutputMarshaller.java#L475

  ObjectTypeNode initialFactNode = ruleBase.getRete().getEntryPointNode( EntryPoint.DEFAULT ).getObjectTypeNodes().get( ClassObjectType.InitialFact_ObjectType );
  

2. When the InputMarshaller tries to unmarshall a marshalled session and it's using a (new) ruleBase that doesn't contain an ObjectTypeNode that descibes the InitialFact_ObjectType, then a NPE is thrown.

• This is caused because the sinks that are given to the MarshallerReaderContext (used in InputMarshaller.readSession) do not contain the InitialFact_ObjectType.
• These sinks:
  • come from KnowledgeBaseImpl.ruleBase which
    • contains a .rete attribute which
      • contains .entrypoints (Map<EntryPoint, EntryPointNode> which
        • contains EntryPointNode's which
          • contains objectTypeNodes (Map<ObjectType, ObjectTypeNode>) which
            • contain objectTypeNodes
              • which should contain a ObjectTypeNode describing the InitialFactNode.

I can't figure out where to add this information when initializing the KnowledgeSession or KnowledgeBase for unmarshalling – or whether the unmarshalling process should take care of this.

The NPE is thrown here (the node variable at line 65 is null):

ConcurrentNodeMemories.getNodeMemory(NodeMemory) line: 65	
ReteooStatefulSession(AbstractWorkingMemory).getNodeMemory(NodeMemory) line: 1018	
InputMarshaller.readSession(ReteooStatefulSession, DefaultAgenda, long, boolean, MarshallerReaderContext) line: 237	
InputMarshaller.readSession(MarshallerReaderContext, int, ExecutorService, Environment, SessionConfiguration) line: 209