image_block_only.json

{
    "type": "image",
    "block_id": "fake_block_id",
    "image_url": "https://api.slack.com/img/blocks/bkb_template_images/beagle.png",
    "alt_text": "image1",
    "title": {
        "type": "plain_text",
        "text": "image1"
    }
}