Merge pull request #272 from ImMin5/feature-service-accont-auto-sync

None type error when check workspace references value

src/spaceone/identity/service/job_service.py

@@ -505,7 +505,7 @@ def _create_workspace(
 
             if workspace_vo.name != name:
                 params.update({"name": name})
-            if workspace_vo.references not in reference_id:
+            if workspace_vo.references and reference_id not in workspace_vo.references:
                 params.update({"references": workspace_vo.references + [reference_id]})
 
             params.update({"last_synced_at": datetime.utcnow()})