Examine source code of Shift to Calendar

{
  "manifest_version": 3,
  "name": "Shift to Calendar",
  "description": "Select shift text on any page and add to Google Calendar in one click. Any format supported.",
  "version": "1.0.0",
  "permissions": [
    "contextMenus",
    "storage",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "homepage_url": "https://shiftschedulemaker.net",
  "browser_specific_settings": {
    "gecko": {
      "id": "shift-to-calendar@shiftschedulemaker.net",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}