**Note: we can reuse the changes/commits from **https://github.com/interledger/open-payments/pull/504

During a grant request, a client should be able to specify any subjects they might want to acquire information on from the RS. GNAP achieves this through the subject field, though this is currently unimplemented in the OP spec.

Subject Information field specification

TODOs:

• Add subject field (with sub_id_formats and sub_ids keys) to the Grant Request body spec:

Example:

"subject":  {
     "sub_id_formats": ["uri"],
     "sub_ids":["<wallet address>"]
}

• Allow access_token to be optional in request body
  • Grant request body should allow for either access_token or subject to be optional: i.e. a grant request can contain just access_token, just subject, both access_token and subject, but cannot be empty