[Openid-specs-ab] Issue #1840: OpenID4VCI: properties in Credential Issuer Metadata get dropped with JSON-LD (openid/connect)

[judith.kahrer]

New issue 1840: OpenID4VCI: properties in Credential Issuer Metadata get dropped with JSON-LD
https://bitbucket.org/openid/connect/issues/1840/openid4vci-properties-in-credential-issuer

Judith Kahrer:

The Credential Issuer Metadata as defined in [10.2.3](https://openid.bitbucket.io/connect/openid-4-verifiable-credential-issuance-1_0.html#section-10.2.3) must contain a `credentials_supported` parameter.  
According to [10.2.3.1](https://openid.bitbucket.io/connect/openid-4-verifiable-credential-issuance-1_0.html#section-10.2.3.1) this parameter is an array of JSON objects with certain properties \(some of which are mandatory\).   
[Appendix E 1.3.2 Credential Issuer Metadata](https://openid.bitbucket.io/connect/openid-4-verifiable-credential-issuance-1_0.html#name-credential-issuer-metadata-4) adds even more properties for a supported credential object. In particular, it emphasis JSON-LD processing. 

When processing a supported credential using JSON-LD, any properties that cannot be expanded to an IRI, i.e. that do not have a matching term definition via `@context`, will be dropped \(see step 4 in [overview of expansion algorithm for JSON-LD 1.1 ](https://www.w3.org/TR/json-ld11-api/#overview-3)\). The only required context in OpenID4VCI is `https://www.w3.org/2018/credentials/v1` \(via the VC Data Model as defined in E1.3.2\). Consequently, many of the parameters defined in 10.2.3.1 and E1.3.2 will be ignored when applying JSON-LD processing. So, the current draft does not support \(is incompatible with\) JSON-LD processing because the resulting object won’t confirm with the specification as required properties are also ignored. 

Suggested solution: Create and publish a dedicated context for OpenID4VCI that enables JSON-LD processing for supported credential objects.