FULL PRODUCT VERSION :
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux xxxxxx 3.11.10-100.fc18.x86_64 #1 SMP Mon Dec 2 20:28:38 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
Not sure if this is a bug, but seems it should be. Classes in java.base which are not exported ccan still be seen by the java execution command ('java').

For example:

$ java sun.security.x509.X500Name
Error: Main method not found in class sun.security.x509.X500Name, please define the main method as:
   public static void main(String[] args)
or a JavaFX application class must extend javafx.application.Application

Attempting to import this class gives a correct error:

x.java:1: error: package sun.security.x509 is not visible
import sun.security.x509.X500Name;
                   ^
  (package sun.security.x509 is declared in module java.base, which does not export it to the unnamed module)
1 error


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
$ java sun.security.x509.X500Name

and observe error relating to main method not error about unexported class.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I would expect an error relating to unexported class.
ACTUAL -
An error relating to missing main method is produced.

REPRODUCIBILITY :
This bug can be reproduced always.