Currently, we only do mirrored reads for the first update statement in an update command. For parity, we will only do a mirrored read for the first update statement in a bulkWrite command. Optionally, we can also do mirrored reads for the first update statement for each namespace in a bulkWrite. That will require some work in MirrorMaestroImpl::_mirror to support multiple mirrored requests from a single command invocation. Since mirrored reads are best-effort, this is optional.