Any other transaction utilizing credentials will already refresh them,
as necessary, through the use of AuthorizedHttp. `get_token_value` is
one unique case where we're not actually attaching the credentials to
the HTTP request, but rather using one if its attributes as the payload.
The request, itself, is unauthenticated, so it doesn't know to refresh
on its own. Rather, the caller needs to make sure that the id_token
payload is for a currently-valid set of credentials.
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