To recreate: 1. Make an extended attribute and set it as "Staff interface mandatory:" 2. Using Postman or cURL or whatever you like, make an API request to localhost:8080 AND localhost:8081 3. You'll get a response like "Missing mandatory extended attribute (type=SOMEATTR)" It would be good if we could pass something to define which interface to mock/follow? Or add a api_mandatory option to extended attributes?