Add volume dimensions to package
Package may have its own volume (which is often defined by WxLxH). So in this case it must replace the total volume of the package based on the content. Also a common case is the pallet for which we know the ground surface from the type but the height only when packaging. So we could store on the package type some dimensions and copy them on the package (like for the weight). Then when we have all three dimension we can compute the volume.