Dynamic way of binding class type to element

Question

I have this xml format as output from different http request.

<transaction>
<respmsg>...</respmsg>
<respcode>0000</respcode>
<status>success</status>
</transaction>

Below is my Transaction Class Representation

@root
class Transaction {
   @Element
   public ResponseMessage respmsg;
   @Element
   public int respcode;
   @Element
   public String status;
}

An abstract class representation of "respmsg" property

abstract class ResponseMessage {

}

This is fairly easy to map to a Class object. However "respmsg" is different for every request for login request the respmsg might be

<respmsg>
   <firstname>John</firstname>
   <lastname>Doe</lastname>
   <mobilephone>1234</mobilephone>
   <email>johndoe@test.com</email>
</respmsg>


class LoginResponseMessage extends ResponseMessage {
    @Element
    public String firstname;

    @Element
    public String lastname;

    @Element
    public String mobilephone;

    @Element
    public String email;
}

and for location request it might be

<respmsg>
   <address1>121 121 UAE Bldg, dubai</address1>
   <address2/>
   <city>Dubai</city>
   <postalcode>121</postalcode>
   <region>dubai</region>
</respmsg>

class LocationResponseMessage extends ResponseMessage {
    @Element
    public String address1;

    @Element
    public String address2;

    @Element
    public String postalcode;

    @Element
    public String region;
}

How do I design my class so that it knows what type of class to use for the respmsg during desserialization?

String xmlData = retrieve(urls[0]); //retrieve fetches the string xml from the http request
Serializer serializer = new Persister();
Reader reader = new StringReader(xmlData);
Transaction t = serializer.read(Transaction.class, reader, false);

Answer 1

As requested, posting my comment as an answer:

---

What about adding an attribute to the <respmsg> tag stating which type it is?

For example:

<respmsg type="LocationResponseMessage">