I'm trying to get my head around how I'd configure some @Extension-annotated
classes I'm creating. I've got a few different ones in the plugin I'm working
on. I really don't want to have to use static properties of my implementation
of hudson.Plugin: that's ugly and difficult to test. But
Jenkins.getInstance().getExtensionList(QueueTaskDispatcher.class)
returns an empty list when run from Plugin#start(), and ExtensionList#add() is
deprecated. So how do I configure my @Extensions before they get used?
