Spring Security Support multiple SingleLogoutService bindings

Expected Behavior

Should be specify mulitple SingleLogoutService bindings. This would be incorporated into Saml2LogoutRequestFilter, Saml2LogoutResponseFilter and OpenSamlMetadataResolver.

Current Behavior

RelyingPartyRegistration only support adding a single singleLogoutServiceBinding.

Context

Trying to migrate off of Spring SAML Extension. Existing behavior in the Spring SAML Extension allows support for multiple SLO bindings.

Have not identified a workaround. This is preventing us from migrating since we currently support both REDIRECT and POST bindings for the SingleLogoutService and are unable to migrate all customers to utilize a single binding.

Comment From: jzheaux

Hi, @emopti-jrufer, thanks for the suggestion and the PR. We'll take a look and see if it's feasible to add into the next milestone release.