Standalone stub generation task fails resolving classes

If you create a Java class (Foo) and a Groovy class (Bar extends Foo), and then run the stub generation Ant task (GenerateStubsTask), it'll fail because it now does all the phases up to semantic analysis which attempts to resolve all class references. AFAIU the stub generation is supposed to be run before Javac. So it should be prepared that some Java classes the Groovy code depends on aren't compiled yet.