Added prefixes.properties file, so that classes with package-prefix can ...

...be dynamically loaded. This is necessary because otherwise every class in the app and runtime would need to be inspected, hurting performance especially for large apps.

Your app found a problem in IOSClass: https://github.com/google/j2objc/issues/377. Dynamic class loading fails with inner classes because Java uses $ to separate outer and inner class names, while j2objc uses _ (since $ is illegal in an Obj-C name). Follow issue 377 to be notified when this is publicly available.

If you want to work around issue 377, make the inner class outer.