Reformatting and re-indenting once and for all, to avoid polluting the history again in future! Sorry, it had to be -- I can't face staring at 2-space indents in Java.
As a first step to shrinking the repository, deleted all packages which were not imported by fc.xml.diff or one of its dependencies.
Somehow it worked fine to build the project with Ant, but when I built it which Eclipse, these annotations caused errors ('cannot convert NonNull to Annotation'). Removed them for now; to be investiated later.
Getting towards a sane project directory structure! Updated build settings to cope with the new paths.
Now there are no remaining subproject dependencies!