Consumer Credential as defined using default context-mapper default is invalid JSON-LD

[jason-fox]

Specifically, looking at:
https://github.com/FIWARE/data-space-connector/blob/main/k3s/consumer.yaml#L209-L210

"config": {
    "context": "https://www.w3.org/2018/credentials/v1",
    "supportedCredentialTypes": "VerifiableCredential,UserCredential,OperatorCredential"
}

Defines three terms - VerifiableCredential,UserCredential,OperatorCredential.

Looking at the supplied @context : https://www.w3.org/2018/credentials/v1 I can see that VerifiableCredential is a defined term within the context (it is actually an @protected term so it cannot be overwritten) but the user-defined terms UserCredential,OperatorCredential are not. Furthermore the dynamic mapped terms such as firstName, lastName, eMail and role are also not defined in the base context.

The claim appears as:

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1"
    
  ],
  "type": [
    "VerifiableCredential",
    "OperatorCredential"
  ],
  "credentialSubject": {
    "firstName": "Alice",
    "lastName": "User",
    "eMail": "[email protected]",
    "roles": [ "OPERATOR"]
  }
}

Which expands to:

[
  {
    "https://www.w3.org/2018/credentials#credentialSubject": [
      {}
    ],
    "@type": [
      "https://www.w3.org/2018/credentials#VerifiableCredential",
      "OperatorCredential"
    ]
  }
]

Which drops all the useful stuff.

The correct JSON-LD is something like: "@context" : [ "https://www.w3.org/2018/credentials/v1", "some+other.jsonld"]
where some+other.jsonld maps to the missing terms

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    {
      "OperatorCredential": "https://example.org/OperatorCredential",
      "firstName": "https://schema.org/firstName",
      "lastName": "https://schema.org/lastName",
      "eMail": "https://schema.org/eMail",
      "roles": "https://example.org/roles"
    }
  ],
  "type": [
    "VerifiableCredential",
    "OperatorCredential"
  ],
  "credentialSubject": {
    "firstName": "Alice",
    "lastName": "User",
    "eMail": "[email protected]",
    "roles": [ "OPERATOR"]
  }
}

Which results in the following expansion:

[
  {
    "https://www.w3.org/2018/credentials#credentialSubject": [
      {
        "https://schema.org/eMail": [
          {"@value": "[email protected]"}
        ],
        "https://schema.org/firstName": [
          { "@value": "Alice"}
        ],
        "https://schema.org/lastName": [
          {"@value": "User"}
        ],
        "https://example.org/roles": [
          { "@value": "OPERATOR"}
        ]
      }
    ],
    "@type": [
      "https://www.w3.org/2018/credentials#VerifiableCredential",
      "https://example.org/OperatorCredential"
    ]
  }
]

[jason-fox]

The simplest fix would be host an @context file on GH-Pages adding a file like claim-models.jsonld:

{
  "@context": {
      "OperatorCredential": "https://example.org/OperatorCredential",
      "firstName": "https://schema.org/firstName",
      "lastName": "https://schema.org/lastName",
      "eMail": "https://schema.org/eMail",
      "roles": "https://example.org/roles"
    }
}

And amendng the configuration to point to https://fiware.github.io/data-space-connector/claim-models.jsonld

 "context": ["https://www.w3.org/2018/credentials/v1",  "https://fiware.github.io/data-space-connector/claim-models.jsonld"]