Throw warning when associated class is not DBObjectClass derived
Throw warning when associated class is not DBObjectClass derived

piotras/midgard-core,piotras/midgard-core,midgardproject/midgard-core,piotras/midgard-core,midgardproject/midgard-core,piotras/midgard-core,midgardproject/midgard-core,midgardproject/midgard-core