@Override
    public void serviceAdded(ServiceConfig cfg) throws Exception {
        if (server != null) {
            if (server != cfg.server()) {
                throw new IllegalStateException("cannot be added to more than one server");
            } else {
                return;
            }
        }

        server = cfg.server();

        // Auto-detect the primary port number and its session protocol after the server started.
        server.addListener(portConfigHolder);
    }
An {@link HttpService} which handles SAML APIs, such as consuming an assertion, retrieving a metadata
or handling a logout request from an identity provider.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlService.java