The reality is we have a bunch of things:

* CAS protocol with no SLO
* CAS protocol with tacked on SAML2 XML format but our own logic
* Proper SAML2 SLO Profile
* Proper SAML2 SLO Front-Channel Profile (sorry I can't remember what the actual profile names are).
* whatever else someone thinks of down the line

Ideally, we need a way to encapsulate all of this and be able to handle it.  I'm not sure a LogoutManagerImpl satisfies that requirements, but I agree that a single logOutOfService method will not be sufficient either.