code: public function serialize($entity)
      {
          if (!$this->container->has('hydra.serializer')) {
              throw new \LogicException('The HydraBundle is not registered in your application.');
          }
  
          return $this->container->get('hydra.serializer')->serialize($entity, self::FORMAT);
      }
docs: Shortcut to serialize an entity into JSON-LD
  
  This method uses the Hydra Serializer service and therefore requires
  that the HydraBundle is registered.
  
  @param object $entity The entity to serialize
  
  @return string The entity serialized in JSON-LD
  
  @throws \LogicException If HydraBundle is not available