src/Security/EventListener/Token/ClientListener.php
public function created(JWTCreatedEvent $event)
    {
        $data = $event->getData();
        $this->accessor->setValue($data, $this->property, $this->getSignature());
        $event->setData($data);
    }
public function created(JWTCreatedEvent $event)
    {
        $data = $event->getData();
        $this->accessor->setValue($data, $this->property, $this->getSignature());
        $event->setData($data);
    }
Add the client signature to the token

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