$object->buchungsgruppen_id(undef) if $object->buchungsgruppen_id && !$self->bg_by->{id}->{ $object->buchungsgruppen_id };
# 3. Look up name if supplied.
$object->buchungsgruppen_id(undef) if $object->buchungsgruppen_id && !$self->bg_by->{id}->{ $object->buchungsgruppen_id };
# 3. Look up name if supplied.