At this moment I received a DWG drawing with both Extended and Object data. To convert this data I first have to read with:

Autodesk AutoCAD Civil 3D

then read with

Autodesk AutoCAD Map 3D Object Data

and merge all features on the autocad_entity_handle

Am I doing something wrong or is this the only way to get both attributes?

Is it possible build a transformer that uses both reading engines because I think that would make the reader faster than current.