Manifest factory does our caching for us, but it doesn't handle the
case that the file being cached is modified.
Until this bites somebody, this just shouldn't be changed. We end up
reloading our webapp often enough that none of the current developers
have cared about this.
Personally, I don't see the need. If you have to change the factory,
just bounce the webapp or tomcat. Seems like this would add code that
would need to be tested and maintained and doesn't add any value
except to save a little time for a developer.