make serialize more robust for deep models with empty parts
make serialize more robust for deep models with empty parts

guumaster/mongoosastic,mongoosastic/mongoosastic,mallzee/mongoosastic,hdngr/mongoosastic,mallzee/mongoosastic,teambition/mongoosastic,mallzee/mongoosastic,francesconero/mongoosastic,avastms/mongoosastic,teambition/mongoosastic,hdngr/mongoosastic,avastms/mongoosastic,ennosol/mongoosastic,francesconero/mongoosastic,guumaster/mongoosastic,mongoosastic/mongoosastic,hdngr/mongoosastic,ennosol/mongoosastic,mongoosastic/mongoosastic,guumaster/mongoosastic