code: func BatchSizeValue(maxMessages, absoluteMaxBytes, preferredMaxBytes uint32) *StandardConfigValue {
  	return &StandardConfigValue{
  		key: BatchSizeKey,
  		value: &ab.BatchSize{
  			MaxMessageCount:   maxMessages,
  			AbsoluteMaxBytes:  absoluteMaxBytes,
  			PreferredMaxBytes: preferredMaxBytes,
  		},
  	}
  }
docs: // BatchSizeValue returns the config definition for the orderer batch size.
  // It is a value for the /Channel/Orderer group.