Examine source code of Accept-Language per site

{
  "manifest_version": 3,
  "name": "Accept-Language per site",
  "version": "0.4.0",
  "homepage_url": "https://github.com/sorz/accept-language-per-site",
  "author": "Shell Chen",
  "description": "Change Accept-Language for different sites",
  "browser_specific_settings": {
    "gecko": {
      "id": "addon-accept-lang@sorz.org",
      "strict_min_version": "128.0"
    }
  },
  "icons": {
    "48": "icon.svg",
    "96": "icon.svg"
  },
  "permissions": [
    "declarativeNetRequestWithHostAccess",
    "storage"
  ],
  "optional_host_permissions": [
    "*://*/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "options_ui": {
    "page": "options.html"
  }
}