Unexpected NullPointerException can be thrown on establishing of connection
with LDAP server using initial context factory
com.sun.jndi.ldap.LdapCtxFactory.
The exception stack trace like the one below is reported:
Caused by: java.lang.NullPointerException: null
        at com.sun.jndi.ldap.LdapClient.authenticate(LdapClient.java:300)
        at com.sun.jndi.ldap.LdapCtx.connect(LdapCtx.java:2791)
        at com.sun.jndi.ldap.LdapCtx.<init>(LdapCtx.java:319)
        at com.sun.jndi.ldap.LdapCtxFactory.getUsingURL(LdapCtxFactory.java:192)
        at com.sun.jndi.ldap.LdapCtxFactory.getUsingURLs(LdapCtxFactory.java:210)
        at com.sun.jndi.ldap.LdapCtxFactory.getLdapCtxInstance(LdapCtxFactory.java:153)
        at com.sun.jndi.ldap.LdapCtxFactory.getInitialContext(LdapCtxFactory.java:83)
        at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:684)
        at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:313)
        at javax.naming.InitialContext.init(InitialContext.java:244)
        at javax.naming.InitialContext.<init>(InitialContext.java:216)
        at javax.naming.directory.InitialDirContext.<init>(InitialDirContext.java:101)

I suspect that it could be caused by JVM defect JDK-8205330
(https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8205330), though, Icould not reproduce the issue with BER logs (using
com.sun.jndi.ldap.trace.ber).
Thus, I cannot prove that "Notice of Disconnection" was issued by LDAP
server.

As NPE is not an expected exception which can be thrown on InitialDirContext
creation, the exception handling logic on InitialDirContext creation usually
only handles NamingExceptions. As result, the unhandled NPE can cause crashes
of applications.

It does not look like there is a work around for the issue apart form
strengthening the exception handling logic to catch all RuntimeExceptions

Environment:
JVM Version: 1.8.0_161-b12
OS : Linux version: 3.10.0-514.6.1.el7.x86_64 arch: amd64 cores: 4