Auth plugins hard code the "method" that is used to name them in the config file. This prevents reuse, and forces a new Plugin for each mod_auth mechanism in Apache HTTPD. Since there is already a handful of "external" plugins, we will have a cross-preoduct of auth plugins; one for each mechanism X mapping scheme.

This was discussed at the Hackathon

From: https://etherpad.openstack.org/p/keystone-juno-hackathon

Remove method name from auth plugins (so the method name is owned by keystone.conf)

One place where this shows up is that the "kerberos" method requires a new AuthPlugin for existing functionality, such as using the Default Domain. The same is true for SAML, or OpenID connect.