src/Security/EventListener/Token/UuidListener.php
public function created(JWTCreatedEvent $event)
    {
        $data = $event->getData();
        $user = $event->getUser();
        $this->accessor->setValue($data, $this->property, $user->getUuid());
        $event->setData($data);
    }
public function created(JWTCreatedEvent $event)
    {
        $data = $event->getData();
        $user = $event->getUser();
        $this->accessor->setValue($data, $this->property, $user->getUuid());
        $event->setData($data);
    }
Add the user uuid to the token

@param \Lexik\Bundle\JWTAuthenticationBundle\Event\JWTCreatedEvent $event