I'm all for JavaConfig and Groovy support for this in preference to the XSD! :)

How would it work for the user configuring it then? Would we provide an `AbstractFactoryBean` that provides the correct configuration options via CTOR? Then the property placeholder stuff could replace the values like if using XML but the user would do any wiring they need and inject any services required (like Codecs, Consumers, and the like).

This would be a general-purpose solution as people are already asking how to use Reactor modules in XD, so it makes sense to have something that will work for Streams and anything else we come up with down the road.