Allow for url to be a list

This solves interoperability issues, see:
- https://git.pleroma.social/pleroma/pleroma/-/issues/3253
- https://socialhub.activitypub.rocks/t/fep-fffd-proxy-objects/3172/30?u=helge
- https://data.funfedi.dev/0.1.1/#url-parameter

lib/pleroma/web/activity_pub/object_validators/article_note_page_validator.ex

@@ -53,6 +53,14 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.ArticleNotePageValidator do
 
   defp fix_url(%{"url" => url} = data) when is_bitstring(url), do: data
   defp fix_url(%{"url" => url} = data) when is_map(url), do: Map.put(data, "url", url["href"])
+  defp fix_url(%{"url" => url} = data) when is_list(url) do
+    if is_map(List.first(url)) do
+      Map.put(data, "url", List.first(url)["href"])
+    else
+      Map.put(data, "url", List.first(url))
+    end
+  end
+
   defp fix_url(data), do: data
 
   defp fix_tag(%{"tag" => tag} = data) when is_list(tag) do

test/pleroma/web/activity_pub/object_validators/article_note_page_validator_test.exs

@@ -39,6 +39,25 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.ArticleNotePageValidatorTest
       %{valid?: true} = ArticleNotePageValidator.cast_and_validate(note)
     end
 
+    test "note with url validates", %{note: note} do
+      note = Map.put(note, "url", "https://remote.example/link")
+      %{valid?: true} = ArticleNotePageValidator.cast_and_validate(note)
+    end
+
+    test "note with url array validates", %{note: note} do
+      note = Map.put(note, "url", ["https://remote.example/link"])
+      %{valid?: true} = ArticleNotePageValidator.cast_and_validate(note)
+    end
+
+    test "note with url array validates if contains a link object", %{note: note} do
+      note = Map.put(note, "url", [%{
+        "type" => "Link",
+        "href" => "https://remote.example/link"
+      }])
+      %{valid?: true} = ArticleNotePageValidator.cast_and_validate(note)
+    end
+
+
     test "a note with a language validates" do
       insert(:user, %{ap_id: "https://mastodon.social/users/akkoma_ap_integration_tester"})
       note = File.read!("test/fixtures/mastodon/note_with_language.json") |> Jason.decode!()