private Zendesk(AsyncHttpClient client, String url, String username, String password, Map<String, String> headers) {
    this.logger = LoggerFactory.getLogger(Zendesk.class);
    this.closeClient = client == null;
    this.oauthToken = null;
    this.client = client == null ? new DefaultAsyncHttpClient() : client;
    this.url = url.endsWith("/") ? url + "api/v2" : url + "/api/v2";
    if (username != null) {
        this.realm = new Realm.Builder(username, password)
                .setScheme(Realm.AuthScheme.BASIC)
                .setUsePreemptiveAuth(true)
                .build();
    } else {
        if (password != null) {
            throw new IllegalStateException("Cannot specify token or password without specifying username");
        }
        this.realm = null;
    }
    this.headers = Collections.unmodifiableMap(headers);
    this.mapper = createMapper();
}
 

public ClickHouseClient(String endpoint, String username, String password) {
	this.endpoint = endpoint;

	this.optParams = new ArrayList<>();
	
	AsyncHttpClientConfig config = new DefaultAsyncHttpClientConfig.Builder()
			.setRealm(new Realm.Builder(username, password)
					.setUsePreemptiveAuth(true)
					.setScheme(Realm.AuthScheme.BASIC)
					.build())
			.build();

	this.httpClient = new DefaultAsyncHttpClient(config);
}
 

private void kerberosChallenge(Realm realm,
                               Request request,
                               HttpHeaders headers) throws SpnegoEngineException {

	Uri uri = request.getUri();
	String host = withDefault(request.getVirtualHost(), uri.getHost());
	String challengeHeader = SpnegoEngine.instance(realm.getPrincipal(),
			realm.getPassword(),
			realm.getServicePrincipalName(),
			realm.getRealmName(),
			realm.isUseCanonicalHostname(),
			realm.getCustomLoginConfig(),
			realm.getLoginContextName()).generateToken(host);
	headers.set(AUTHORIZATION, NEGOTIATE + " " + challengeHeader);
}