State.py: add function getAvailableTypeList for state type.

product/ERP5Workflow/Document/State.py

@@ -92,3 +92,15 @@ class State(IdAsReferenceMixin("state_", "prefix"), XMLObject, XMLMatrix):
     for tr in self.getDestinationValueList():
       ref_list.append(tr.getReference())
     return ref_list
+
+  def getAvailableTypeList(self):
+    """This is a method specific to ERP5. This returns a list of state types, which are used for portal methods.
+    """
+    return (
+            'draft_order',
+            'planned_order',
+            'future_inventory',
+            'reserved_inventory',
+            'transit_inventory',
+            'current_inventory',
+            )
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