Variable Persistence Overwrites NULL Values over Persisted Values

Drools Flow
=========

For non-String variables (Serializ..ble, Entities, etc..), Drools overwrites NULLs when a (JPA) process is resumed ( a workitem is completed ).

1. Here is a use case: a List ( ArrayList ) is passed to the process in start as a parameter
2. First work item sees ( maps in ) the List, and can work with it inside the work item handler
3. First work item does not complete: process goes to sleep.
4. When the session is reloaded, the first work item is completed
5. All the persisted variables ( including the "list" ) are restored
6. Second work item is taking in the list ( it maps in )
7. However at this point it is NULL

It seems that when the context is closed, after resolving variables, the following (WorkItemNodeInstance):

VariableScopeInstance variableScopeInstance = ( VariableScopeInstance )
resolveContextInstance( VariableScope.VARIABLE_SCOPE, mapping.getValue() );

does no longer have the restored variables, and rather NULLs, since internally variables are compared with a "result map" that was passed to the previous work item.

This means that persisted variables are restored internally, but then overwritten internally by NULLs.

/Anatoly