Read this credential's authority

Reports the authority the presented credential carries: the project it acts in, which of that project's two environments, and the scopes the service will enforce for it. The answer comes entirely from the verified principal, so there is no parameter that could name another project and no way for the reply to describe anything but the caller itself. It requires a principal and no scope, because every value in it is a property of the credential being presented rather than of anything the credential may reach: a caller that could not read this could still act, and would simply be acting without being able to say where. A signed-in member is not accepted — a session's authority is an organization and it names its project per request, so there is no single answer to give one.