InteractionWorkflow.py: add interaction variable support.

product/ERP5Workflow/Document/InteractionWorkflow.py

@@ -303,7 +303,7 @@ class InteractionWorkflow(IdAsReferenceMixin("", "prefix"), Workflow):
       sci = None
 
       # Update variables.
-      tdef_exprs = tdef.var_exprs
+      tdef_exprs = tdef.objectValues(portal_type='Transition Variable')
       if tdef_exprs is None: tdef_exprs = {}
       status = {}