AbstractMappedObject has discriminator false

[Markus Pallo]

I am trying to use sling.ocm and started extending my classes from 
AbstractMappedObject.
After inserting my objects, the nodes do not have ocm_classname attribute.
So i expect its because AbstactMappedObject has "discriminator=false" 
and its not possible to overwrite these tag.

Is there a special reason why AbstractMappedObject has discriminator=false.

Markus