Credential Offer credentials field is not matching the OID4VCI Draft 12

[ntsbs]

The credential offer response in rfc001 is not compatible with the referenced version of the OID4VCI spec.

The credentials field should be an

An array of unique strings that each identify one of the keys in the name/value pairs stored in the credentials_supported Credential Issuer metadata property. OID4VCI Draft 12 Section 4.1.1

The non-normative example from the spec is as follows:

{
   "credential_issuer": "https://credential-issuer.example.com",
   "credentials": [
      "UniversityDegreeCredential",
      "org.iso.18013.5.1.mDL"
   ],
   "grants": {
      "authorization_code": {
         "issuer_state": "eyJhbGciOiJSU0Et...FYUaBy"
      },
      "urn:ietf:params:oauth:grant-type:pre-authorized_code": {
         "pre-authorized_code": "adhjhdjajkdkhjhdj",
         "user_pin_required": true
      }
   }
}

[lalc]

This change is accepted. The earlier version was coming from EBSI conformant wallet implementation specs.