Leadimage functionality not "kicking in" on Plone 5.1.5

My content type has leadimage.ILeadImageBehaviour registered.
This same code works on older versions of Plone and on Plone 5.2

Leadimage is enabled on Plone 5.2rc3 and not enabled on Plone 5.1.5
This is a snippet from the code.

 <property name="behaviors">

Apparently the name has changed from plone.app.contenttypes.behaviors.leadimage.ILeadImage
to plone.app.contenttypes.behaviors.leadimage.ILeadImageBehavior

But plone.app.upgrade has an upgrade step to fix this iirc.

The problem in our scenario is that our developer created the addon TTW on Plone 5.2 then moved it to the filesystem.
Then we tested the resulting filesystem addon on Plone 5.1.

Our solution at the moment is to use plone.app.contenttypes.behaviors.leadimage.ILeadImage as this is still supported in Plone 5.2 since the latest plone.app.contenttypes declares it as a formerdottedname

@jensens Is that already documented in the upgrade-guide for 5.2?

Just for reference: Same with RichText behavior.

Which one? I lost track where are all those guides are :wink:

@iham did you add a note to that guide?

Thanks @espenmn this is important. I may be looking in the wrong places but I haven't seen this information documented.