Replace UserAuthInterface with UserAuthenticationInterface for Drupal 11 Support

FYI, if you're seeing an error message that looks something like the following, you may be dealing with a module that has conflicts between the old UserAuthInterface and the new UserAuthenticationInterface:
"TypeError: Drupal\commerce_checkout\Plugin\Commerce\CheckoutPane\Login::__construct(): Argument #8 ($user_auth) must be of type Drupal\user\UserAuthInterface, Drupal\mail_login\AuthDecorator given"

If you had a problem with Mail Login and your search led you here, you need to downgrade to Mail Login 3.x.

I'm wondering if we shouldn't use the union type and allow both interfaces?

UserAuthInterface|UserAuthenticationInterface this way we can support both? But maybe not necessary since Commerce 3 is only D10.3+

I'll defer judgement on that since this is my first time encountering this exact scenario with compatibility issues for a drop-in replacement in Core.

I'd presume it'd be the nice thing to do support both until it's actually dropped in Drupal 12. There may be other modules that continue to reference the old methods and those may break Commerce Checkout if only the new methods are supported. Case in point is Mail Login 4.x and that's the module that brought me here.

I'm not familiar with using a union type to address this scenario to provide options. How would that work?

See the latest commit.

Ok sorry, I did this too quickly... Based on the interface, we have to call a different method... Perhaps dropping support of the old interface is the cleanest solution here... But I wonder why the tests are failing then?

For members who already upgraded Drupal Core to ^10.3 and wanted to update Mail Login to ^4.0.

here is the Commerce Core 8.x-2.39 compatible patch for this issue queue.

Automatically closed - issue fixed for 2 weeks with no activity.

I think the right fix is to mark Commerce 2.x incompatible with Mail Login 4 as Commerce isn't going to be compatible with D11 and retain compatibility with D9 and D10 < 10.3

@vipin.j mail_login 4.0.3 supports both old and the new interface so you feel free to upgrade.