public static SnapshotMBeanServerConnection newSnapshot(MBeanServerConnection mbsc) {
   final InvocationHandler ih = new SnapshotInvocationHandler(mbsc);
   return (SnapshotMBeanServerConnection)
       Proxy.newProxyInstance(
           Snapshot.class.getClassLoader(),
           new Class[] {SnapshotMBeanServerConnection.class},
           ih);
 }
 private static void checkStub(Remote stub, Class<? extends Remote> stubClass) {
   // Check remote stub is from the expected class.
   //
   if (stub.getClass() != stubClass) {
     if (!Proxy.isProxyClass(stub.getClass())) {
       throw new SecurityException("Expecting a " + stubClass.getName() + " stub!");
     } else {
       InvocationHandler handler = Proxy.getInvocationHandler(stub);
       if (handler.getClass() != RemoteObjectInvocationHandler.class) {
         throw new SecurityException(
             "Expecting a dynamic proxy instance with a "
                 + RemoteObjectInvocationHandler.class.getName()
                 + " invocation handler!");
       } else {
         stub = (Remote) handler;
       }
     }
   }
   // Check RemoteRef in stub is from the expected class
   // "sun.rmi.server.UnicastRef2".
   //
   RemoteRef ref = ((RemoteObject) stub).getRef();
   if (ref.getClass() != UnicastRef2.class) {
     throw new SecurityException(
         "Expecting a " + UnicastRef2.class.getName() + " remote reference in stub!");
   }
   // Check RMIClientSocketFactory in stub is from the expected class
   // "javax.rmi.ssl.SslRMIClientSocketFactory".
   //
   LiveRef liveRef = ((UnicastRef2) ref).getLiveRef();
   RMIClientSocketFactory csf = liveRef.getClientSocketFactory();
   if (csf == null || csf.getClass() != SslRMIClientSocketFactory.class) {
     throw new SecurityException(
         "Expecting a "
             + SslRMIClientSocketFactory.class.getName()
             + " RMI client socket factory in stub!");
   }
 }