serivces.yml

services:
    ss.serializer.serializer_listener:
        class: SerializerListener
        arguments:
            - '@router' # surely you want to inject liipimagine stuff
        tags:
            - { name: jms_serializer.event_listener, event: serializer.post_serialize, method: onPostSerialize, class: SuperObjectWithPath, format: json, direction: serialization }

UrlSerializerListener.php

<?php

use Symfony\Bundle\FrameworkBundle\Routing\Router;
use JMS\Serializer\EventDispatcher\Event;
use Symfony\Component\Form\Util\PropertyPath;

class SerializerListener
{
    private $router;
    private $map;

    public function __construct(Router $router, array $map)
    {
        $this->router = $router;
        $this->map = $map;
    }

    public function onPostSerialize(Event $event)
    {
        $object = $event->getObject();
        $config = $this->map[get_class($object)];

        $params = array_map(function($path) use ($object) {
            $propertyPath = new PropertyPath($path);
            return $propertyPath->getValue($object);
        }, $config['params']);

        $url = $this->router->generate($config['route'], $params);

        $event->getVisitor()->addData('url', $url);
    }
}