We currently inherit nexus.repository.url from the jboss-parent pom, and then use the property in expressions that determine the complete URL of repos in the 'repositories' and 'pluginRepositories' section.

Maven 4 doesn't like this and fails to build. Jan Bliznak has a solid theory as to why at https://wildfly.zulipchat.com/#narrow/channel/174184-wildfly-developers/topic/Maven.204/near/558751932 – basically that Maven 4 wants to know the repository info before it looks up the parent, and it can't interpolate (aka resolve) the expression until it gets the parent.

Simple solution is to declare the property locally.