I haven't fully understood the ticket so perhaps I'm wrong, but it seems like a proper deprecation would be `self.is_required = kwargs['required']` (maybe that won't work)? As it is now, this seems like a backwards compatible change and the deprecation warning isn't serving any purpose other than to alert to that issue -- may we should just list it in the release notes and skip the warning (or at least make it DeprecationWarning right away)?