HostControllerRegistrationHandler is the handler in charge of registering a remote host controller in the domain.

The currently implemented rules to allow remote host connections are:

1. Reject any Host Controller below WF23
2. For non-mixed domains, reject any remote host that is not running on a paired stability level; we only allow the DEFAULT – DEFAULT, COMMUNITY – COMMUNITY, PREVIEW – PREVIEW, and EXPERIMENTAL – EXPERIMENTAL pairs.
3. For any mixed domain, we only allow the following pairs: DEFAULT – DEFAULT, COMMUNITY – COMMUNITY

However, right now we are even running mixed domain tests where we use a remote host controller running EAP 7.4 (it will report null stability level) and a WildFly server, which by default runs in COMMUNITY stability level.

The issue here that when the remote Host Controller does not advertise any stability level, we use the local Product Conf default stability level, which is COMMUNITY for WildFly.

This situation falls back into rule #3 above and we allow the connection even when the remote host is not running on the same stability level than WildFly