Problems with Java adapter for CLI / Desktop Applications

Hello.
I’m trying to use the Java adapter for CLI/Desktop applications in
order to integrate keycloak services with my app.
I have followed the steps described in the documentation, but at the
execution of the instruction

keycloak.loginDesktop();

It fails with the following message :

Cannot invoke “org.keycloak.common.util.KeycloakUriBuilder.clone()” because the return value of “org.keycloak.adapters.KeycloakDeployment.getAuthUrl()” is null

I can’t understand if it is a problem of keycloak server configuration, or I have
to specify some other field in the JSON client configuration file.
Has anyone else had the same problem?

Thank You
Claudio Cordara