In WildFly 31, stability levels were introduced and that server is the first server that starts by default under the community stability level.

We have to introduce it in the mixed domain test suite so we can check how a Domain Controller launched using the current server under development behaves against a legacy Host Controller, in this case, WildFly 31. This will allow us to test the same set of mixed domain tests we have been testing in the past with a pair of a Domain Controller – Hostcontroller running both under community stability level.