Remove OpenSaml deprecation warnings

[Brummolix]

Expected Behavior

When running Spring Security with saml support it should not log deprecation warnings.

Current Behavior

While using OpenSamlLogoutRequestResolver the application logs for example:

09:09:04 [WARN ] DEPRECATED#warn:125 - Java class method 'setSessionIndex', (interface org.opensaml.saml.saml2.core.SessionIndex): This will be removed in the next major version of this software; replacement is setValue

Context

Deprecated (for removal) methods should not be used any longer.
I will provide a PR with a fix.