[keycloak-user] RestEasy Client doesn't support logging in as a service account

[Marc Spehlmann]

I have tried to configure the RestEasy client to use a service account for one of my confidential clients. The Java code to configure the client looks like:

```
import org.keycloak.admin.client.Keycloak;
import org.keycloak.admin.client.KeycloakBuilder;

class Scratch {

    public static void main(String[] args) {
        final String server = "localhost:8082";
        final String realm = "master";
        final String clientSecret = "00000000-0000-0000-0000-000000000000";
        final String clientId = "MyClient";

        Keycloak keycloak = KeycloakBuilder.builder()
                .serverUrl(server)
                .realm(realm)
                .clientId(clientId)
                .clientSecret(clientSecret)
                .build();

        keycloak.realm("master")
                .clients()
                .findAll();
    }
}
```

This will fail with the exception:

```
Exception in thread "main" java.lang.IllegalStateException: username required
	at org.keycloak.admin.client.KeycloakBuilder.build(KeycloakBuilder.java:131)
	at Scratch.main(scratch_41.java:17)
```

I have a workaround, but my question is, is there any plan to support service-accounts with the keycloak client?