code: public <S, T> ToMarshaller<S, T> findMarshaller(Class<S> source, Class<T> target, Class<? extends Annotation> qualifier) {
  		return findMarshaller(new ConverterKey<S,T>(source, target, qualifier == null ? DefaultBinding.class : qualifier));
  	}
docs: Resolve a Marshaller with the given source and target class.
  The marshaller 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 qualifier The qualifier for which the marshaller must be registered