Making content type linkable in TinyMCE under Plone 5

I'm working on a pull request for one of our add-ons to make a content type linkable in TinyMCE, but tests are failing in Plone 5 bulds:

can somebody tell me if that's still needed under Plone 5 and/or how to implement it?

do we have documentation on add-on migration that included those kind of features?

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