Mapping methods that contain an @MappingTarget parameter should be usable as property mapping methods.

The generated code should cover the following cases:

• The @MappingTarget method could return void or the target type. In case the target type is returned, we should call the setter with that value.
• The target property may be null. I guess we should hand in a new instance of the target type (call constructor or a factory method).

Any thoughts?