ToCap() will be okay even if empty struct
ToCap() will be okay even if empty struct

zombiezen/go-capnproto2,hodduc/go-capnproto2,hodduc/go-capnproto2,zombiezen/go-capnproto,tpukep/caps,zombiezen/go-capnproto2,zombiezen/go-capnproto