As part of working on SERVER-59204 we discovered that the FindCommandRequest IDL structure does not enforce that certain members like "filter" are actually owned, despite having type "object_owned_nonempty_serialize". We should consider whether it makes sense to enforce ownership in the IDL for owned types. If we do enforce then changes would include:

1) Making default empty objects owned. For the "filter" field mentioned above, a query that is parsed with no filter will result in an empty object, which are not considered owned despite having no associated buffer.

2) Making setters call BSONObj::getOwned() on input arguments