[cas-dev] Pass on authentication method

[Marvin S. Addison]

You should not have to modify SamlAuthenticationMetaDataPopulator,
provided each of your authentication methods maps to a distinct+
credentials class.  If that is the case, you can simply set the
userDefinedMappings property on that class with how your credentials
classes should map to SAML authentication method URNs.

Dealing with different URNs for the _same_ credentials class is another
matter.  In our case we have two distinct types of principals that
authenticate via LDAP, a level 2 user and a level 1 user (in NIST 800-63
parlance).  Both of these are UsernamePasswordCredentials cases, so we'd
need to provide a different implementation of
AuthenticationMetaDataPopulator to handle this case.

I wonder if others have use cases like ours above.  Please speak up if
that is the case.

Thanks,
Marvin