@type t() :: %Volley.PersistentSubscription.Subscription{
  connection: Spear.Connection.t(),
  group_name: String.t(),
  opts: Keyword.t(),
  ref: reference(),
  stream_name: String.t()
}

A subscription structure which stores connection details for any persistent subscription

Acks and nacks may be sent with the :connection and :ref fields.

Spear.ack(subscription.connection, :subscription.ref, event_ids)
Spear.nack(subscription.connection, :subscription.ref, event_ids, action: :retry)

If the Volley.PersistentSubscription producer is used in GenStage-mode (with broadway?: false), each Spear.Event.t/0 will have one of these structs in its .metadata.subscription field which can be used for acks and nacks.