// Note that this is not the only marshalling that is done.
// RococoaTypeMapper also gets involved.
if (arg == null)
return null;
if (arg instanceof NSObjectByReference)
return new IDByReference(); // this will be filled in with an id by
// the called code, and then marshalled to an NSObject by fillInReferences
// TODO - passing existing inout, not just out
return arg;
}