MessageUtil isn't meant to be public...
ConcurrentMapFactory -> Internal_ConcurrentMapFactory (this clearly communicates what it is, also automatically excludes it from the JavaDoc)
Moved Version into f.core, as it's advanced-user stuff.
Remove class from the JavaDoc that are, I suppose, only accidentally public.
Rewritten package-level JavaDocs (as they were outdated, unfocused, etc).