Be scared of methods that cannot be renamed
Be scared of methods that cannot be renamed

Summary:
In practice, checking for just `root` isn't enough, as we've seen that ProGuard annotations might only exist for keepnames.
Then again, we only need to be concerned about additional implementations for interfaces, so we can refine the check for that.

Reviewed By: ssj933

Differential Revision: D18076749

fbshipit-source-id: a3651eba263c41721198b7fce419ff4cf9639e5a

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