Use json:api’s /type/id/field_name URLs for fetching relationships

[agarzola]

Currently, we’re using the ?include=field_name query string parameter format which is optional (currently available in Drupal’s JSON API module’s implementation), but not necessarily supported by all json:api implementations. Requests to /type/id/field_name and /type/id/relationships/field_name should be made in parallel to the main request.

• /type/id/field_name fetches the related object(s)
• /type/id/relationships/field_name fetches the relationship itself (which might include metadata)

This method should probably be the default, with the query string parameter method being an opt-in configuration parameter.