How can I get a google IdToken?

Ionic Native
1

I am using this plugin: https://github.com/EddyVerbruggen/cordova-plugin-googleplus, but I did everything without firebase.

After the user selects his Gmail correctly I get an object with a lot of different user informations

and on the backend side I use Java and followed this tutorial: https://developers.google.com/identity/sign-in/web/backend-auth

Now I got the problem that I only get an Access Token via the googleplus plugin, but I need an IDToken, but the Tutorial says it is possible to get the IdToken if I send a webclientId. This is the code I used:

this.googlePlus.login({webclientId:'778525824123-83qa65tspdfd5c6i6roquf3dd41m3nk8.apps.googleusercontent.com'})
.then(res => {
  console.log(res);
}
)
.catch(err => console.error(err));

Maybe there is something wrong with my webclientId? I don’t know.