We are using OpenID4Java library in code. How can we upgrade to OpenID Connect as recommended but Google: https://developers.google.com/accounts/docs/OpenID
The OpenID4Java library only supports OpenID 2.0 and 1.0. For OpenID Connect you'll need to consider a different library. You can pick one from the (Java) options listed on the following page: http://openid.net/developers/libraries/