Ash.DataLayer.upsert

You're seeing just the callback upsert, go back to Ash.DataLayer module for more information.
Link to this callback

upsert(arg1, arg2, list)

View Source (optional)

Specs

upsert(Ash.Resource.t(), Ash.Changeset.t(), [atom()]) ::
  {:ok, Ash.Resource.t()} | {:error, term()}