code: public static Batch create(String carrierAccount, String serviceLevelToken, LabelFileType labelFileType,
  			String metadata, BatchShipment[] shipments)
  			throws AuthenticationException, InvalidRequestException, APIConnectionException, APIException {
  		Map<String, Object> params = new HashMap<String, Object>();
  		params.put("default_carrier_account", carrierAccount);
  		params.put("default_servicelevel_token", serviceLevelToken);
  		params.put("label_filetype", labelFileType.toString());
  		params.put("batch_shipments", shipments);
  		return request(RequestMethod.POST, classURL(Batch.class), params, Batch.class, null);
  	}
docs: Create a batch. This function corresponds to POSTing to
  https://api.goshippo.com/batches endpoint documented at
  https://goshippo.com/docs/reference#batches-create
  
  @param carrierAccount
  Carrier account ID used if not provided in individual
  shipments
  @param serviceLevelToken
  Associated service level token used if not provided in
  shipments
  @param labelFileType
  Print format of the label
  @param metadata
  Optional user content associated with the batch
  @param shipments
  Array of {@link BatchShipment} objects that will be added to
  the batch
  @return The newly created Batch object