Thanks for the patch @arnaldop. I could not test the patch as it wouldn't app...

Thanks for the patch @arnaldop. I could not test the patch as it wouldn't apply anymore and would need a reroll. A few things which can be improved in the patch

1. +optional: + - domain +

   can be changed to

   +optional: + - domain:domain +
2. I guess this service and method don't exist anymore, so this will have to be replaced with alternatives. + calls: + - [setDomainAliasLoader, ['@?domain_alias.loader']]
3. This will also require writing of an update hook that would change the entity schema. /** + * The login destination domains. + * + * @var array + */ + public $domains = []; +
4. This will have to be changed and written by injecting a dependency. + $system_domains = \Drupal::entityTypeManager()->getStorage('domain')->loadMultipleSorted();

And as you already mentioned we will require a good manual testing and tests as well. Let's keep it open for now and see if we can get more support in completing this feature.