Finding Generic Setup import code for behaviors in typeinfo

Generic Setup .xml files are processed by import/export handlers, most of the time in exportimport.py files which subclas from XMLAdapterbase and has an attributes attribute with a dict defining the keywords.

But where can I find out where the 'behaviors' property from a content type in typeinfo is processed (if it's Dexterity). I've hunted through a few packages (plone.dexterity, plone.dexterity, plone.app.content, Products.CMPlone), but I can't find it.

Reason I want to inspect the code is to see if purge='False' is supported properly on behaviors in GS, I think it's not.

I believe it's handled by the generic PropertyManagerHelpers in https://github.com/zopefoundation/Products.GenericSetup/blob/master/Products/GenericSetup/utils.py#L603

It should handle purge="false".