A sample application that demonstrates how the Google OAuth2 library can be used to authenticate
against a locally running Keycloak server with a registered public client where using PKCE is required.
Please note that before running this sample application, a local Keycloak server must be
running and a PKCE enabled client must have been defined. Please see
samples/keycloak-pkce-cmdline-sample/scripts/initialize-keycloak.sh for further