A new rule must be added to catch applications using EAP 6 Singleton Services mechanism to implement a HA Singleton, which is not supported by EAP 7. EAP 7 includes a new API for building such services, thus the user should become aware of that too.

See https://docs.jboss.org/author/display/WFLY10/How+do+I+migrate+my+application+from+AS7+to+WildFly#HowdoImigratemyapplicationfromAS7toWildFly-HASingleton

When: app classes use org.jboss.as.clustering.singleton.SingletonService
Perform: the user must reimplement the HA Singleton using the new API included with EAP 7.