remove some more unneeded fields
remove some more unneeded fields

jen20/capnproto-java,nchinmay/capnproto-java,nchinmay/capnproto-java,jen20/capnproto-java,dwrensha/capnproto-java,jen20/capnproto-java,dwrensha/capnproto-java,dwrensha/capnproto-java,nchinmay/capnproto-java