postland/lib/postland_web/controllers/outbox_controller.ex

defmodule PostlandWeb.OutboxController do
   use PostlandWeb, :controller

   alias ActivityPub.Headers

  def get(conn, _params) do
    json = %{
      "@context" => "https://www.w3.org/ns/activitystreams",
      "summary" => "",
      "type" => "OrderedCollection",
      "totalItems" => 0,
      "orderedItems" => []
    }

    if Headers.verify(conn.method, conn.request_path, conn.req_headers) do
      Plug.Conn.send_resp(conn, 200, Jason.encode!(json))
    else
      Plug.Conn.send_resp(conn, 403, "forbidden")
    end
  end
end