@callback load(Ash.Resource.t(), Ash.Resource.Actions.action()) ::
  atom() | [atom()] | Keyword.t()

A load statement to be applied before this notifier receives the notification.

The loaded fields are merged onto notification.data before notify/1 is called. If multiple notifiers request the same fields with the same arguments, the calculation dependency resolver ensures they are only loaded once.

The return value can be anything accepted by Ash.Query.load/2, including %Ash.Query.Calculation{} structs for multi-level dependency resolution (e.g. a PubSub notifier building one inner load per publication).