removes empty option in JSON tag
removes empty option in JSON tag

option can not be empty in JSON tag

Signed-off-by: chavacava <4e83c7095b75809ae37cc39c0160a8a7d552ccc5@gmail.com>

mqliang/etcd,ajityagaty/etcd,ajityagaty/etcd,ajityagaty/etcd,mqliang/etcd,etcd-io/etcd,mqliang/etcd,etcd-io/etcd,etcd-io/etcd