RestServiceProvider.php

<?php

namespace Drupal\rest;

use Drupal\Core\DependencyInjection\ContainerBuilder;
use Drupal\Core\DependencyInjection\ServiceProviderInterface;
use Drupal\rest\LinkManager\LinkManager;
use Drupal\rest\LinkManager\RelationLinkManager;
use Drupal\rest\LinkManager\TypeLinkManager;
use Symfony\Component\DependencyInjection\ChildDefinition;
use Symfony\Component\DependencyInjection\Reference;

/**
 * Provides BC services.
 *
 * These services are not added via rest.services.yml because the service
 * classes extend classes from the HAL module. They also have no use without
 * that module.
 */
class RestServiceProvider implements ServiceProviderInterface {
    
    /**
     * {@inheritdoc}
     */
    public function register(ContainerBuilder $container) {
        $modules = $container->getParameter('container.modules');
        if (isset($modules['hal'])) {
            // @deprecated in Drupal 8.3.x and will be removed before Drupal 9.0.0.
            //   Use hal.link_manager instead.
            // @see https://www.drupal.org/node/2830467
            $service_definition = new ChildDefinition(new Reference('hal.link_manager'));
            $service_definition->setClass(LinkManager::class);
            $container->setDefinition('rest.link_manager', $service_definition);
            // @deprecated in Drupal 8.3.x and will be removed before Drupal 9.0.0.
            //   Use hal.link_manager.type instead.
            // @see https://www.drupal.org/node/2830467
            $service_definition = new ChildDefinition(new Reference('hal.link_manager.type'));
            $service_definition->setClass(TypeLinkManager::class);
            $container->setDefinition('rest.link_manager.type', $service_definition);
            // @deprecated in Drupal 8.3.x and will be removed before Drupal 9.0.0.
            //   Use hal.link_manager.relation instead.
            // @see https://www.drupal.org/node/2830467
            $service_definition = new ChildDefinition(new Reference('hal.link_manager.relation'));
            $service_definition->setClass(RelationLinkManager::class);
            $container->setDefinition('rest.link_manager.relation', $service_definition);
        }
    }

}