layout_container.json

{
  "type": "layout",
  "label": "Layout",
  "rows": [
    {
      "items": [
        {
          "block": {
            "type": "container",
            "child_blocks": [
              {
                "type": "divider",
                "block_id": "child"
              }
            ],
            "width": "standard",
            "is_collapsible": false,
            "default_collapsed": false,
            "has_header_divider": false,
            "block_id": "container",
            "title": {
              "type": "plain_text",
              "text": "Container"
            }
          }
        }
      ]
    }
  ],
  "block_id": "layout"
}