Strongly recommended for the best service experience. Be aware that it will also increase latency when checking the status of a batch operation. If update_mask is provided, only the specified fields in Job are updated. Otherwise all the fields are updated. A field mask to restrict the fields that are updated. Only top level fields of Job are supported. If update_mask is provided, The Job inside JobResult will only contains fields that is updated, plus the Id of the Job. Otherwise, Job will include all fields, which can yield a very large response.