Media Duplicates Module Compatibility

Problem/Motivation

If a site is using using the Media Duplicates → module and the Brandfolder module, the former will log warnings when trying to evaluate with Brandfolder-sourced media. E.g.

Unable to create checksum for brandfolder_image. Unable to get a definition for media type brandfolder_image.

This is a minor issue because the Brandfolder module paradigm largely prevents duplicates already, but it would be nice to provide a plugin for the duplicates module so sites using a variety of media sources can use it without these warnings cropping up.