UserAuthDecorator.php

<?php

declare (strict_types=1);
namespace Drupal\user_auth_decorator_test;

use Drupal\user\UserAuthInterface;

/**
 * Helper to validate UserAuthInterface BC layers are functional.
 */
class UserAuthDecorator implements UserAuthInterface {
    
    /**
     * Constructs a UserAuthDecorator object.
     *
     * @param \Drupal\user\UserAuthInterface $inner
     *   The inner User.Auth service.
     */
    public function __construct(UserAuthInterface $inner) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function authenticate($username, $password) {
        return $this->inner
            ->authenticate($username, $password);
    }

}