Users of custom IDP solutions may require non standard attributes to be submitted along with the token request. In our case we require a specific attribute called "resource" to be submitted along with the normal token request attributes of client_id, grant_type etc. This resource parameter informs the roles that are returned with the JSON auth token.
We would like to propose that to increase the compatibility of Jamf Connect with custom IDP solutions, you allow the ability to configure custom attributes to be submitted along with the client_id etc during the token request. This will allow for more flexibility in the product in the future.