The Thorntail Maven plugin reads a property called wildfly-swarm.useUberJar to determine whether it should launch in classpath mode or uberjar mode. All properties we have are named swarm.* except of this one. We should make this consistent, but at this point, we shouldn't break compatibility.
Suggestion is to read swarm.useUberJar first and, if it doesn't exist, read wildfly-swarm.useUberJar. We'll document the new name (maybe also mention the old name in a footnote?), but we'll respect the old name as well.