Invoke correct Logout method

[Cantor, Scott]

There is no API for doing a custom logout, no, at least if one ignores the administrative logout feature which I guess could be sort of twisted into one.

Under no circumstances are you meant to have any specific knowledge of cookie usage or anything of that nature, those are implementation details.

What I will say is that whether it's supported or not, actually clearing every cookie issued by the IdP is going to prevent a session from being recognized, whether the rest of the state is gone or not, but that is again not a commitment that it always would work in the future.

It's not a crazy feature request to consider an external callout in the midst of the logout process, at least as long as control is properly returned to the IdP afterward. But that ignores many modes of logout that would not in general permit such a thing.

-- Scott