[Openid-specs-ab] Issue #1539: Server metadata under specified (openid/connect)

[Travis Spencer]

New issue 1539: Server metadata under specified
https://bitbucket.org/openid/connect/issues/1539/server-metadata-under-specified

Travis Spencer:

[Section 8.1](https://openid.net/specs/openid-4-verifiable-presentations-1_0.html#name-authorization-server-metada) of the 21 June 2022 draft of OIDC4VP under specifies server metadata. It simply says:

> A JSON object defining the formats, proof types and algorithms of verifiable presentations and verifiable credentials that a RP supports. Valid **values** include…

What is a value of a JSON object? There’s no normative or non-normative reference to a JSON spec, but RFC 7591 and OpenID.Registration have such references to RFCs that are updated to [RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259#section-4) which says:

> An object structure is represented as a pair of curly brackets surrounding zero or more **name/value pairs \(or members**\).

From this, I can’t make out what 8.1 is saying exactly. \(Sorry I’m being pedantic, but it’s important to be exact in specs, right?\)

As a result, one could argue that the following is valid metadata:

```json
{
    "vp_formats_supported": {
        "key1": [
            { "value": "jwt_vp" },
            "my_good_proof_type",
            "my_good_algorithm"
        ],
        "key2": [
            { "value":  "ldp_vp" },
            "my_other_good_proof_type",
            "my_other_good_algorithm"
        ]
    }
}
```

From the example of client metadata in 8.2.3.1, one could infer the expected structure of this JSON object. \(For this reason, I view this issue as minor\). However, the spec should clearly state this in 8.1 IMHO.