--- a/jdk/src/share/classes/com/sun/security/auth/module/UnixSystem.java	Mon Dec 06 10:48:20 2010 +0800
+++ b/jdk/src/share/classes/com/sun/security/auth/module/UnixSystem.java	Mon Dec 06 10:48:57 2010 +0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,9 +25,6 @@
 
 package com.sun.security.auth.module;
 
-import javax.security.auth.*;
-import javax.security.auth.login.*;
-
 /**
  * <p> This class implementation retrieves and makes available Unix
  * UID/GID/groups information for the current user.
@@ -92,6 +89,6 @@
      * @return the supplementary groups for the current Unix user.
      */
     public long[] getGroups() {
-        return groups;
+        return groups == null ? null : groups.clone();
     }
 }