in protobuf/src/internal.rs [78:83]
fn get_size(&self) -> usize {
0
+ 1 + sizeof_varint(*(&self.time) as u64)
+ self.contents.iter().map(|s| 1 + sizeof_len((s).get_size())).sum::<usize>()
+ self.time_ns.as_ref().map_or(0, |_| 1 + 4)
}