New in version 0.7: Added Dexterity Data Manager (see: datamanagers.py)
New in version 0.9.2: Added Zope Schema Field Manager (see: fieldmanagers.py)
Dexterity Content Types are handled by a Data Manager (IDataManager) and a Field Manager (IFieldManager) respectively. Also see Adding a custom data manager. Integrators just have to add route providers for their Dexterity Content Types (see: Adding a custom route provider) and the JSON API should handle the heavy lifting.
plone.jsonapi.routes checks only the permission on the content object to be at least cmf.ModifyPortalContent. Checks on the field level will be added in future versions.