Altering existing route for translation overview page ie: entity.node.content_translation_overview

Question

I have followed this documentation page : https://www.drupal.org/docs/drupal-apis/routing-system/altering-existing-routes-and-adding-new-routes-based-on-dynamic-ones in attempt to alter access of translation overview page ie: www.example.com/node/1/translations

<?php

namespace Drupal\link_enhancements\Routing;

use Drupal\Core\Routing\RouteSubscriberBase;
use Symfony\Component\Routing\Route;
use Symfony\Component\Routing\RouteCollection;

/**
 * Listens to the dynamic route events.
 */
class RouteSubscriber extends RouteSubscriberBase {

  /**
   * {@inheritdoc}
   */
  public function alterRoutes(RouteCollection $collection) {

    $route_name = "entity.node.content_translation_overview";
    var_dump($collection->get($route_name)); exit;
    if ($route = $collection->get($route_name)) {
      $requirements = $route->getRequirements();
      unset($requirements['_permission']);
      // if both role then only we will allow ...code will go here.....
      $route->setRequirement('_access', 'FALSE');
    }

  }

}


services:
  link_enhancements.route_subscriber:
    class: Drupal\link_enhancements\Routing\RouteSubscriber
    tags:
      - { name: event_subscriber }

But below route output is null and similar code works for other routes but requirement to alter translation overview route which returns null.

$route_name = "entity.node.content_translation_overview";
    var_dump($collection->get($route_name)); exit;

core/modules/content_translation/src/Routing/ContentTranslationRouteSubscriber.php

route is added in core module by below code and I have searched and tried but not sure how can we alter such routes, please suggest.

if ($entity_type->hasLinkTemplate('drupal:content-translation-overview')) {
        $route = new Route(
          $entity_type->getLinkTemplate('drupal:content-translation-overview'),
          [
            '_controller' => '\Drupal\content_translation\Controller\ContentTranslationController::overview',
            'entity_type_id' => $entity_type_id,
          ],
          [
            '_entity_access' => $entity_type_id . '.view',
            '_access_content_translation_overview' => $entity_type_id,
          ],
          [
            'parameters' => [
              $entity_type_id => [
                'type' => 'entity:' . $entity_type_id,
                'load_latest_revision' => $load_latest_revision,
              ],
            ],
            '_admin_route' => $is_admin,
          ]
        );
        $route_name = "entity.$entity_type_id.content_translation_overview";
        $collection->add($route_name, $route);
      }

Answer 1

It was not working because in content_transaltion module priority was set to -210 so make need to change priority of custom module to -220 and it started working.

public static function getSubscribedEvents() {
    $events = parent::getSubscribedEvents();
    $events[RoutingEvents::ALTER] = ['onAlterRoutes', -220];
    return $events;
  }