8005460: [findbugs] Probably returned array should be cloned

Reviewed-by: xuelei

jdk/src/share/classes/sun/security/krb5/PrincipalName.java

@@ -499,7 +499,7 @@ public class PrincipalName implements Cloneable {
     }
 
     public String[] getNameStrings() {
-        return nameStrings;
+        return nameStrings.clone();
     }
 
     public byte[][] toByteArray() {

jdk/test/sun/security/krb5/name/Immutable.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2013, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8005460
+ * @summary [findbugs] Probably returned array should be cloned
+ */
+
+import sun.security.krb5.PrincipalName;
+
+public class Immutable {
+    public static void main(String[] args) throws Exception {
+        PrincipalName pn1 = new PrincipalName("host/service@REALM");
+        PrincipalName pn2 = (PrincipalName)pn1.clone();
+        pn1.getNameStrings()[0] = "http";
+        if (!pn1.equals(pn2)) {
+            throw new Exception();
+        }
+    }
+}