public function update()
    {
        if (!isset($this->_links->self->href)) {
            return $this;
        }

        $body = json_encode([
            "tracking" => $this->tracking,
        ]);

        $result = $this->client->performHttpCallToFullUrl(
            MollieApiClient::HTTP_PATCH,
            $this->_links->self->href,
            $body
        );

        return ResourceFactory::createFromApiResult($result, new Shipment($this->client));
    }