If I'm understanding this change correctly, this seems important enough that we might want to adjust the wording to make it more explicit – perhaps something like “The ElasticSearch backend relies on the default ``<app.label>.<object_name>.<pk>`` format. If you use ElasticSearch and your custom identifier method returns a different format, you will need to subclass ``ElasticsearchSearchBackend`` and override  ``get_type_and_id`` to handle the custom identifier format”?