public OutputModelObject buildListenerOutputModel(SourceType sourceType) {
		CodeGenerator gen = delegate.getGenerator();
		return new ListenerFile(delegate, gen.getListenerFileName(sourceType));
	}
Build a file with a parser containing rule functions. Use the
 controller as factory in SourceGenTriggers so it triggers codegen
 extensions too, not just the factory functions in this factory.
tool/src/org/antlr/v4/codegen/OutputModelController.java