title: Jackson support for polymorphism without annotations and dedicated bean fields
body: <p>Is there a way to perform serialization/deserialization in Jackson of polymorphic classes w/out using annotations or specialized bean fields?  I have to support class hierarchies that I cannot modify and don't wish to use annotations.</p>
  
  <p>I'd like to be able to designate a synthetic name, which would not be in the classes that I am serializing/deserializing, that would be inserted into the JSON representation and used to identify the type. </p>