title: Polymorphism in RESTFul server
body: <p>I have 3 classes. A is abstract class, B and C extends A.
  I want to be able to get a JSON in a POST (A) and then to decide what type it is and to convert to the correct type. in other words to use only one end point for both B and C. The same I want to do in GET, I want to get a one list that contains B and C objects. 
  Does it possible?</p>