message_response.json

{
    "mrkdwn": true,
    "blocks": [
        {
            "type": "section",
            "block_id": "fake_block_id",
            "text": {
                "type": "mrkdwn",
                "text": "Hello, world!"
            }
        }
    ],
    "text": "",
    "replace_original": false,
    "response_type": "ephemeral"
}