Examine source code of Hephaistos20

{
  "manifest_version": 3,
  "name": "Hephaistos20",
  "description": "Link Hephaistos and Roll20",
  "version": "0.2.3",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "scripting",
    "tabs"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://hephaistos.azurewebsites.net/*/*",
        "https://hephaistos.azurewebsites.net/*",
        "https://hephaistos.online/*",
        "https://hephaistos.online/*/*"
      ],
      "js": [
        "contentscript.js"
      ]
    },
    {
      "matches": [
        "https://app.roll20.net/editor/*"
      ],
      "js": [
        "roll20.js"
      ]
    }
  ],
  "externally_connectable": {
    "matches": [
      "https://hephaistos.azurewebsites.net/*/*",
      "https://hephaistos.azurewebsites.net/",
      "https://hephaistos.online/",
      "https://hephaistos.online/*/*"
    ]
  },
  "icons": {
    "32": "icon32.png",
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "Hephaistos20@example.org"
    }
  }
}