FileRouteProvider.php

<?php

namespace Drupal\file\Entity;

use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Entity\Routing\EntityRouteProviderInterface;
use Symfony\Component\Routing\Route;
use Symfony\Component\Routing\RouteCollection;

/**
 * Provides routes for files.
 */
class FileRouteProvider implements EntityRouteProviderInterface {
    
    /**
     * {@inheritdoc}
     */
    public function getRoutes(EntityTypeInterface $entity_type) {
        $route_collection = new RouteCollection();
        $route = (new Route('/file/{file}/delete'))->addDefaults([
            '_entity_form' => 'file.delete',
            '_title' => 'Delete',
        ])
            ->setRequirement('file', '\\d+')
            ->setRequirement('_entity_access', 'file.delete')
            ->setOption('_admin_route', TRUE);
        $route_collection->add('entity.file.delete_form', $route);
        return $route_collection;
    }

}