What's the purpose of other_platform_oauth_client in google-services.json?

Question

I re-downloaded the google-services.json file for Android from the Firebase console and found that there is suddenly an additional field:

"services": {
    "appinvite_service": {
        "other_platform_oauth_client": [
          {
            "client_id": "xxx.apps.googleusercontent.com",
            "client_type": 2,
            "ios_info": {
              "bundle_id": "com.xxx.xxx",
              "app_store_id": "xxx"
            }
          }
        ]
    }
}

The project has an iOS and Android client, so this entry for Android apparently reference the iOS client.

What is the purpose of that entry?

Answer 1

The purpose:

The client_id (together with client_type) are references to credentials that have been created and accessible to you and your project via the Google Developer Console (https://console.developers.google.com/apis/credentials). These can be used when your app needs more than just an app side interaction with Google Services.

Some examples:

• When you enable OAuth 2.0 to use with your app, as a developer (or console admin) you create one or more new credential entries for the platforms (Android, iOS, web, etc.) that you support. As a result client IDs are generated by Google Developer Console for those credentials. Depending on the needs of your app, you might want to use this client ID, when sending a login request to Google (Google Sign-In), so that later you can authenticate the user with your server before allowing (or denying) user access to your app. More info on this example: https://developers.google.com/identity/sign-in/android/offline-access

• Google Services automatically creates the client IDs and the required credentials in Google Console when setting up certain services (e.g. Firebase, Admob, or Other related services).

I hope this answer does explain the purpose of those values.