authorization Server
OID4VCI: OPTIONAL. Identifier of the OAuth 2.0 Authorization Server (as defined in RFC8414) the Credential Issuer relies on for authorization. If this element is omitted, the entity providing the Credential Issuer is also acting as the AS, i.e. the Credential Issuer's identifier is used as the OAuth 2.0 Issuer value to obtain the Authorization Server metadata as per RFC8414.