Examine source code of Rocket Web Start

{
  "name": "Rocket Web Start",
  "version": "1.5resigned1",
  "description": "This extension helps run Java Web Start applications in all java versions, including OpenJDK 11, Oracle Java 11",
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "javawebstart@rocketsoftware.com",
      "strict_min_version": "50.0"
    }
  },
  "permissions": [
    "nativeMessaging",
    "downloads"
  ],
  "content_scripts": [
    {
      "run_at": "document_idle",
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "contentScript.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "Icon32.png",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "Icon16.png",
    "32": "Icon32.png",
    "48": "Icon48.png",
    "128": "Icon128.png"
  }
}