Undertow subsystem should not depend on clustering code

With WFLY-10352, Undertow subsystem now depends on Clustering code for Clustering's abstraction of the new MSC Service API. For example https://github.com/wildfly/wildfly/blob/master/undertow/src/main/java/org/wildfly/extension/undertow/SingleSignOnSessionFactoryServiceConfigurator.java

As far as I can tell, the org.jboss.as.clustering.common module is bundled in servlet-feature-pack just so Undertow extension can access its API.

This is not correct. Undertow should not have to depend on clustering for this kind of abstraction.
Either these abstractions should be provided by Core or they should not be allowed.