Update example

if (!$message instanceof ChatMessage) {
            throw new UnsupportedMessageTypeException(__CLASS__, ChatMessage::class, $message);
        }

        if (($options = $message->getOptions()) && !$options instanceof MercureOptions) {
            throw new LogicException(sprintf('The "%s" transport only supports instances of "%s" for options.', __CLASS__, MercureOptions::class));
        }

        $options ??= new MercureOptions($this->topics);

        // @see https://www.w3.org/TR/activitystreams-core/#jsonld         $update = new Update($options->getTopics() ?? $this->topics, json_encode([
            '@context' => 'https://www.w3.org/ns/activitystreams',
            'type' => 'Announce',
            'summary' => $message->getSubject(),
        ]), $options->isPrivate(), $options->getId(), $options->getType(), $options->getRetry());

        try {
            $messageId = $this->hub->publish($update);

            $sentMessage = new SentMessage($message, (string) $this);
            $sentMessage->setMessageId($messageId);