The KolabObject interface allows to read&write kolab objects using kolab containers. The interface was a misguided attempt to be able to update libkolab if we have to correct something in the mapping from kolab containers to kde containers. Because there are no standalone KDE containers we have to depend on various parts of KDE for that interface. We also ended up with an ugly interface due to the mismatch between KDE containers and Kolab containers (e.g. relations/tags).
The interface is only used by the kolab-resource in kdepim-runtime, and the kolab-utils, which should be easy enough to port.
The KolabObject interface should be dropped completely, and it's use replaced by the MIMEObject interface (for which we need a better name).