FULL PRODUCT VERSION :
java version "1.6.0_25"
Java(TM) SE Runtime Environment (build 1.6.0_25-b06)
Java HotSpot(TM) Client VM (build 20.0-b11, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
If i use getDiagnoseOptions() of a HotSpotDiagnosticMXBean instance, a classcast exception occures.


REGRESSION. Last worked in version 6u25

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
get HotSpotDiagnosticsMXBean instance and try to get diagnostic options

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
any output like 'options: [<vmoptions>]'
ACTUAL -
Exception in thread "main" java.lang.ClassCastException: [Ljavax.management.openmbean.CompositeData; cannot be cast to java.util.List
at $Proxy0.getDiagnosticOptions(Unknown Source)
at Dummy.main(Dummy.java:17)


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.ClassCastException: [Ljavax.management.openmbean.CompositeData; cannot be cast to java.util.List
at $Proxy0.getDiagnosticOptions(Unknown Source)
at Dummy.main(Dummy.java:17)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.lang.management.ManagementFactory;
import java.util.List;

import javax.management.MBeanServerInvocationHandler;
import javax.management.ObjectName;

import com.sun.management.HotSpotDiagnosticMXBean;
import com.sun.management.VMOption;

public class Dummy2 {
public static void main(String[] args) throws Exception {
ObjectName hsdObjectName = new ObjectName(
"com.sun.management:type=HotSpotDiagnostic");
HotSpotDiagnosticMXBean hsdMXBean = MBeanServerInvocationHandler
.newProxyInstance(ManagementFactory.getPlatformMBeanServer(),
hsdObjectName, HotSpotDiagnosticMXBean.class, false);
List<VMOption> options = hsdMXBean.getDiagnosticOptions();
System.out.printf("options: %1$s\n", options);
}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Get attribute directly from MBeanServer:

import java.lang.management.ManagementFactory;
import java.util.Arrays;

import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.openmbean.CompositeData;

public class Dummy {
public static void main(String[] args) throws Exception {

ObjectName hsdObjectName = new ObjectName(
"com.sun.management:type=HotSpotDiagnostic");
MBeanServer F_server = ManagementFactory.getPlatformMBeanServer();
CompositeData[] attribute = (CompositeData[]) F_server.getAttribute(
hsdObjectName, "DiagnosticOptions");
System.out.printf("Options: %1$s\n", Arrays.toString(attribute));
}
}