Upgrading an Ember Project. What do I do about an ArrayProxy extending the deprecated SortableMixin?

I am attempting to upgrade an old (1.10) Ember project to the latest LTS release (3.8).

One of the things I am struggling with is this line, as Ember.SortableMixin has been deprecated.

ArrayProxy.extend(Ember.SortableMixin).create({ content: [] })

I have heard that we can use computed.sort to replace most occurrences, but what am I to do about this case, where the ArrayProxy is extending the Mixin?

I haven't been able to find much advice about this case online.

Thanks.