Oh, I see.
Actually I was talking out my ass anyway, the reason it's not null is the pg port is borken with respect to
the oracle version. On oracle the supertype
param is defaulted to 'acs_object' but when acs_object is added as an object type the param is set explicitly to null.
On pg, you don't have parameter defaulting so it can't distinguish a supertype you want to have be null from
one where you just want the default.
I think we should special case the acs_object object_type create to leave it null in pg as well.
