FULL PRODUCT VERSION :
java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+166)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+166, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.14393]

A DESCRIPTION OF THE PROBLEM :
II you run a Java 8 compiled program that use the DnsContextFactory it does not work anymore in Java 9.

REGRESSION. Last worked in version 8u121

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) Client VM (build 25.121-b13, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
The follow simple source code lines produce the problem:

Hashtable<String, String> env = new Hashtable();
env.put( "java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory" );
DirContext dns = new InitialDirContext( env );


ERROR MESSAGES/STACK TRACES THAT OCCUR :
javax.naming.NoInitialContextException: Cannot instantiate class:
com.sun.jndi.dns.DnsContextFactory [Root exception is java.lang.IllegalAccessException:
class javax.naming.spi.NamingManager (in module java.naming) cannot access
class com.sun.jndi.dns.DnsContextFactory (in module jdk.naming.dns) because module jdk.naming.dns
does not export com.sun.jndi.dns to module java.naming]
    at java.naming/javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:719)
    at java.naming/javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:305)
    at java.naming/javax.naming.InitialContext.init(InitialContext.java:236)
    at java.naming/javax.naming.InitialContext.<init>(InitialContext.java:208)
    at java.naming/javax.naming.directory.InitialDirContext.<init>(InitialDirContext.java:101)

REPRODUCIBILITY :
This bug can be reproduced always.