Examine source code of Text Caesar Shift Addon

{
  "manifest_version": 2,
  "name": "Text Caesar Shift Addon",
  "version": "1.0.0",
  "description": "Shift letters using a Caesar cipher.",
  "browser_action": {
    "default_title": "Caesar Shift",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "caesar-shift-3cfb228c-9da7-4c00-b5d1-bf129592021c@example.com",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}