code: public final <S, T> void registerUnmarshaller(Class<S> source, Class<T> target, FromUnmarshaller<S, T> converter, Class<? extends Annotation> qualifier) {
  		registerUnmarshaller(new ConverterKey<S,T>(source, target, qualifier == null ? DefaultBinding.class : qualifier), converter);
  	}
docs: Register an UnMarshaller with the given source and target class.
  The unmarshaller is used as follows: Instances of the source can be marshalled into the target class.
  @param source The source (input) class
  @param target The target (output) class
  @param converter The FromUnmarshaller to be registered
  @param qualifier The qualifier for which the unmarshaller must be registered