public static void initialize() {
synchronized (ProviderRegistry.class) {
if (initialized)
return;
IPAuthenticationProvider ipp = new IPAuthenticationProvider();
DigestAuthenticationProvider digp = new DigestAuthenticationProvider();
authenticationProviders.put(ipp.getScheme(), ipp);
authenticationProviders.put(digp.getScheme(), digp);
Enumeration<Object> en = System.getProperties().keys();
while (en.hasMoreElements()) {
String k = (String) en.nextElement();
if (k.startsWith("zookeeper.authProvider.")) {
String className = System.getProperty(k);