Create common alias for all derived classes in XStream

I have an abstract class called Message. There are several implementations (let's call them MessageImpl1, MessageImpl2, ...) of this class and all of them have to be serialized.

Now, default root element is <package.name.MessageImplX>. What I want to do is make all root elements of those classes to be <Message> - just like the base class.

Is there any way to do that without manually adding an alias for every derived class in my project? I don't want to keep track of these every time I make another Message implementation.