@type t() :: %Mobilizon.Activities.Activity{
  __meta__: term(),
  author: Mobilizon.Actors.Actor.t(),
  author_id: term(),
  group: Mobilizon.Actors.Actor.t(),
  group_id: term(),
  id: term(),
  inserted_at: term(),
  message: String.t(),
  message_params: map(),
  object: map(),
  object_id: String.t(),
  object_type: String.t(),
  priority: pos_integer(),
  subject: String.t(),
  subject_params: map(),
  type: String.t()
}