In Section 5.5 of OpenId Connect Core it is not clear whether all implementations should support both “openid” and “userinfo” as ways for specific claims to be returned. There are cases where support for one or other only may be desirable. Assuming that is agreed then an additional metadata entry is needed to communicate what the top level claims in the claims request parameter are supported.
Initial draft …
Add definition: "A JSON array indicating the top-level members of the Claims request JSON object that are supported. Only valid when the “claims_parameter_supported” is present and true.