Currently these only set the values in the json response as attributes of the AuthClient this makes it difficult to know which attributes will be available when, for instance, get_bearer_token sets realm_id but refresh doesn't.
We want results of talking to AuthClient to be able to participate in our strict runtime type checking which involves converting a primitive python type into an attrs dataclass. Having to construct this dictionary out of the AuthClient before we can do that is annoying and error prone.