class EntityModerationRouteProvider

class EntityModerationRouteProvider implements EntityRouteProviderInterface, EntityHandlerInterface {
    
    /**
     * The entity manager.
     *
     * @var \Drupal\Core\Entity\EntityFieldManagerInterface
     */
    protected $entityFieldManager;
    
    /**
     * Constructs a new DefaultHtmlRouteProvider.
     *
     * @param \Drupal\Core\Entity\EntityFieldManagerInterface $entity_manager
     *   The entity manager.
     */
    public function __construct(EntityFieldManagerInterface $entity_manager) {
        $this->entityFieldManager = $entity_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {
        return new static($container->get('entity_field.manager'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getRoutes(EntityTypeInterface $entity_type) {
        $collection = new RouteCollection();
        if ($moderation_route = $this->getLatestVersionRoute($entity_type)) {
            $entity_type_id = $entity_type->id();
            $collection->add("entity.{$entity_type_id}.latest_version", $moderation_route);
        }
        return $collection;
    }
    
    /**
     * Gets the moderation-form route.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   The entity type.
     *
     * @return \Symfony\Component\Routing\Route|null
     *   The generated route, if available.
     */
    protected function getLatestVersionRoute(EntityTypeInterface $entity_type) {
        if ($entity_type->hasLinkTemplate('latest-version') && $entity_type->hasViewBuilderClass()) {
            $entity_type_id = $entity_type->id();
            $route = new Route($entity_type->getLinkTemplate('latest-version'));
            $route->addDefaults([
                '_entity_view' => "{$entity_type_id}.full",
                '_title_callback' => '\\Drupal\\Core\\Entity\\Controller\\EntityController::title',
            ])
                ->setRequirement('_entity_access', "{$entity_type_id}.view")
                ->setRequirement('_content_moderation_latest_version', 'TRUE')
                ->setOption('_content_moderation_entity_type', $entity_type_id)
                ->setOption('parameters', [
                $entity_type_id => [
                    'type' => 'entity:' . $entity_type_id,
                    'load_latest_revision' => TRUE,
                ],
            ]);
            // Entity types with serial IDs can specify this in their route
            // requirements, improving the matching process.
            if ($this->getEntityTypeIdKeyType($entity_type) === 'integer') {
                $route->setRequirement($entity_type_id, '\\d+');
            }
            return $route;
        }
    }
    
    /**
     * Gets the type of the ID key for a given entity type.
     *
     * @param \Drupal\Core\Entity\EntityTypeInterface $entity_type
     *   An entity type.
     *
     * @return string|null
     *   The type of the ID key for a given entity type, or NULL if the entity
     *   type does not support fields.
     */
    protected function getEntityTypeIdKeyType(EntityTypeInterface $entity_type) {
        if (!$entity_type->entityClassImplements(FieldableEntityInterface::class)) {
            return NULL;
        }
        $field_storage_definitions = $this->entityFieldManager
            ->getFieldStorageDefinitions($entity_type->id());
        return $field_storage_definitions[$entity_type->getKey('id')]
            ->getType();
    }

}