I want to get an object as a parameter of a POST request. I got an abstract superclass that is called Promotion and subclasses Product and Percent. Here's how I try to get a request:

@POST
@Consumes(MediaType.APPLICATION_XML)
@Produces(MediaType.APPLICATION_XML)
@Path("promotion/")
public Promotion createPromotion(Promotion promotion) {         
    Product p = (Product) promotion;
    System.out.println(p.getPriceAfter());      

    return promotion;
}

and here's how I use JAXB in classes' definitions:

@XmlRootElement(name="promotion")
@XmlSeeAlso({Product.class,Percent.class})
public abstract class Promotion {
    //body
}


@XmlRootElement(name="promotion")
public class Product extends Promotion {
    //body
}


@XmlRootElement(name="promotion")
public class Percent extends Promotion {
    //body
}

So the problem now is when I send a POST request with a body like this:

<promotion>
  <priceBefore>34.5</priceBefore>
  <marked>false</marked>
  <distance>44</distance>
</promotion>

and I try to cast it to Product (as in this case, fields 'marked' and 'distance' are from Promotion class and 'priceBefore' is from Product class) I get an Exception:

java.lang.ClassCastException: Percent cannot be cast to Product. 

It seems like Percent is chosen as a 'default' subclass. Why is that and how can I get an object that is a Product?