inheritance mapping in dozer

Question

I have Classes hierarchical like this:

Class A{
  private int a;
}
Class B extend A{
  private int b;
}
Class C extend A{
  private int c;
}
Class Prime {
  private int a;
  private A objectA;
}

And I have DTOs for every single classes like this:

Class Dto_A{
  private int a;
}
Class Dto_B extend Dto_A{
  private int b;
}
Class Dto_C extend Dto_A{
  private int c;
}
Class Dto_prime {
  private int prime;
  private Dto_A objectA;
  private int b;
}

How can I map field b from Dto_B in Dto_prime class if objectA instance of Dto_B in dozzer? (as below code:)

Dto_prime dto_p = new Dto_prime();
Dto_B dto_b = new Dto_B();
if(dto_p.objectA instance of Dto_B)
  dto_p.setB(dto_b.getB());

I read inheritance mapping in dozer and add hint in XMLs but it don't work for me and throw exception.

I also try set-method and get-method in XML and do checking like below:

if (objectA instance of Dto_B)
   //do something...

but when i debug it. objectA not instance of none of Class B or Class C.

Note: I persist Prime object with instance of class B as field objectA in Prime.

Any body have suggestion?