Hi,
There are several ways to do that.
The easiest one would be to make your own ObjectTypeManufacturer, which will return null in getType(...) method and register it to your factory.
factory.getStrategy().addOrReplaceTypeManufacturer(Object.class, objectTypeManufacturer);
Something similar is described in the documentation, where string instantiation is customized.
https://mtedone.github.io/podam/#Defining_an_attribute-level_strategy_with_DataProviderStrategy
However, I'm not sure why anyone would want to have all composite types empty. I suppose you
are actually trying to achieve something else.
Thanks, Daniil