Can't find an example for use of user_provider_custom_retrieve_method

Can anyone guide me on how to implement the custom method?

if i understand it right:

Create a class that implements: Illuminate\Contracts\Auth\UserProvider
overwrite the retrieveByCredentials(array $credentials) inside the class to match own needs
now customize the Keycloak-Driver to somehow use the new class

Am i right? am i missing something? WOuld be nice to get some help, maybe someone could point me to a relevant tutorial or something. Thanks.

robsontenorio / laravel-keycloak-guard