code: public function created(JWTCreatedEvent $event)
      {
          $data = $event->getData();
          $user = $event->getUser();
          $this->accessor->setValue($data, $this->property, $user->getUuid());
          $event->setData($data);
      }
docs: Add the user uuid to the token
  
  @param \Lexik\Bundle\JWTAuthenticationBundle\Event\JWTCreatedEvent $event