Make the "nonce" auth request parameter optional in the hybrid "code token" flow

[phavekes]

This issue is imported from pivotal - Originaly created at Dec 7, 2020 by Bart Geesink

Only when issuing an id_token, the nonce must be present. So in the hybrid flow "code token" nonce can be omitted.

Caused by the nimbus library: https://bitbucket.org/connect2id/oauth-2.0-sdk-with-openid-connect-extensions/src/7da4c0b7f9ad10ea08e4ed970d527f7ec37d67f0/src/main/java/com/nimbusds/openid/connect/sdk/AuthenticationRequest.java#lines-1680

Added question in the. code: 1efc29f