SASL configuration failes with NPE

13:58:24,536 WARN  [org.apache.zookeeper.ClientCnxn] (pool-94-thread-1-SendThread(localhost:1100)) SASL configuration failed: javax.security.auth.login.LoginException: java.lang.NullPointerException
	at org.jboss.as.security.RealmDirectLoginModule.validatePassword(RealmDirectLoginModule.java:233)
	at org.jboss.security.auth.spi.UsernamePasswordLoginModule.login(UsernamePasswordLoginModule.java:283)
	at org.jboss.as.security.RealmDirectLoginModule.login(RealmDirectLoginModule.java:157)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at javax.security.auth.login.LoginContext.invoke(LoginContext.java:755)
	at javax.security.auth.login.LoginContext.access$000(LoginContext.java:195)
	at javax.security.auth.login.LoginContext$4.run(LoginContext.java:682)
	at javax.security.auth.login.LoginContext$4.run(LoginContext.java:680)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.login.LoginContext.invokePriv(LoginContext.java:680)
	at javax.security.auth.login.LoginContext.login(LoginContext.java:587)
	at org.apache.zookeeper.Login.login(Login.java:296)
	at org.apache.zookeeper.Login.<init>(Login.java:96)
	at org.apache.zookeeper.client.ZooKeeperSaslClient.createSaslClient(ZooKeeperSaslClient.java:216)
	at org.apache.zookeeper.client.ZooKeeperSaslClient.<init>(ZooKeeperSaslClient.java:119)
	at org.apache.zookeeper.ClientCnxn$SendThread.startConnect(ClientCnxn.java:1001)
	at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1060)
 Will continue connection to Zookeeper server without SASL authentication, if Zookeeper server allows it.