InteractionWorkflow.py: add universal method.

product/ERP5Workflow/Document/InteractionWorkflow.py

@@ -226,4 +226,7 @@ class InteractionWorkflow(IdAsReferenceMixin("interactionworkflow_", "prefix"),
     return None
 
   def _getWorkflowStateOf(self, ob, id_only=0):
-    return None
+    return None
\ No newline at end of file
+
+  def getTransitionList(self):
+    return self.objectValues(portal_type="Interaction")