Convert menu_link_content entities to a menu plugin when replacing menu_link tokens

Doing that now is a BC change

Agreed.

will not work as it won't be the entity object being passed

Well, "sometimes" it is. I came across the problem described in this issue in a pathauto scenario. When editing a node and providing a menu link, the token menu-link is passed in with data being \Drupal\menu_link_content\Entity\MenuLinkContent. However, when bulk updating pathauto with drush, the data being passed for menu-link is an \Drupal\menu_link_content\Plugin\Menu\MenuLinkContent object.

I think, receiving a plugin rather than a content entity makes more sense, but I wasn't able to figure out why pathauto behaves differently here. Any ideas?

OK, found the code where the different data types get passed. It happens in menu_ui_tokens contained in token.tokens.inc:

      // Chained token relationships.
      if ($menu_tokens = \Drupal::token()->findWithPrefix($tokens, 'menu-link')) {
        if ($node->getFieldDefinition('menu_link') && $menu_link = $node->menu_link->entity) {
          /** @var \Drupal\menu_link_content\MenuLinkContentInterface $menu_link */
          $replacements += \Drupal::token()->generate('menu-link', $menu_tokens, ['menu-link' => $menu_link], $options, $bubbleable_metadata);
        }
        else {
          $url = $node->toUrl();
          if ($links = $menu_link_manager->loadLinksByRoute($url->getRouteName(), $url->getRouteParameters())) {
            $link = _token_menu_link_best_match($node, $links);
            $replacements += \Drupal::token()->generate('menu-link', $menu_tokens, ['menu-link' => $link], $options, $bubbleable_metadata);
          }
        }
      }

When editing the node in the UI, the if-statement ($node->getFieldDefinition('menu_link') && $menu_link = $node->menu_link->entity) returns true and therefore uses the MenuLinkContentIniterface, i.e. the content entity.

When using drush with bulk update, this if-statement returns FALSE and it uses the link from the menu_link_manager, i.e. a plugin.

Any idea, why the first version doesn't also load a plugin but the content entity instead?

OK, I've changed the MR accordingly. Removed the original change and added the new one.

I have updated the MR to work with the OO hooks.