static Function<? super HttpClient, LoginClient> newDecorator(WebClient webClient,
                                                                  String username, String password) {
        return delegate -> new LoginClient(delegate, webClient, username, password);
    }
A Nacos client that is responsible for
<a href="https://nacos.io/en-us/docs/auth.html">Nacos Authentication</a>.
nacos/src/main/java/com/linecorp/armeria/internal/nacos/LoginClient.java