Examine source code of Simple Clock Extension

{
  "manifest_version": 3,
  "name": "Simple Clock Extension",
  "version": "1.1",
  "description": "Shows a live clock in a popup.",
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "simple-clock-v2@example.com",
      "strict_min_version": "109.0"
    }
  }
}