[scim] Error extensibility in SCIM - meeting follow up

[Jennifer Schreiber <[e-mail]>]

Thanks everyone for a great discussion yesterday at the meeting. We discussed error handling as relevant to scim events draft and RFC 7644.

Mainly, the big question that came up:
Is there any extensibility method for the error messages ("urn:ietf:params:scim:api:messages:2.0:Error"), similar to Section 3.3 of RFC 7643<https://datatracker.ietf.org/doc/html/rfc7643#section-3.3>? Can error messages, as well as the other scim messages defined in Section 8.2 of RFC 7644<https://datatracker.ietf.org/doc/html/rfc7644#section-8.2> be extended?

Section 3.12 of RFC 7644<https://datatracker.ietf.org/doc/html/rfc7644#section-3.12> is a bit vague about the matter.

This came up for my internally, as the error message is not meeting my implementation needs. We're requiring an additional field, errorCode. Anjali also mentioned the need for an jsonPath field.

During the meeting, we talked through a couple ideas (that I will review in the next meeting) such as below, but we kept coming back to the same extensibility question. I wanted to open up the discussion here prior to the meeting.

```
   {
     "schemas": ["urn:ietf:params:scim:api:messages:2.0:Error", "urn:ietf:params:scim:api:extension:messages:2.0:AdvancedError"],
     "scimType":"mutability"
     "detail":"Attribute 'id' is readOnly",
     "status": "400"
     "urn:ietf:params:scim:api:extension:messages:2.0:AdvancedError": {
         "errorCode": "ABC-1235"
     }
   }
```

Thanks,
Jen