Use void as the PrivateType.
Use void as the PrivateType.

`void` acts correctly in covariant and contravariant positions by not accepting
any values (except null).

polybuildr/clutz,rehmsen/clutz,rehmsen/clutz,polybuildr/clutz,dpurp/clutz,angular/clutz,polybuildr/clutz,dpurp/clutz,angular/clutz,angular/clutz,dpurp/clutz,rehmsen/clutz