code: @Get("json")
  	public final Representation getSerialNumbersForPasses(final Representation entity) {
  		Request request = getRequest();
  		Map<String, Object> requestAttributes = request.getAttributes();
  		String deviceLibraryIdentifier = (String) requestAttributes.get("deviceLibraryIdentifier");
  		String passTypeIdentifier = (String) requestAttributes.get("passTypeIdentifier");
  		String passesUpdatedSince = (String) requestAttributes.get("passesUpdatedSince");
  		LOGGER.debug("getSerialNumbersForPasses - deviceLibraryIdentifier: {}", deviceLibraryIdentifier);
  		LOGGER.debug("getSerialNumbersForPasses - passTypeIdentifier: {}", passTypeIdentifier);
  		LOGGER.debug("getSerialNumbersForPasses - passesUpdatedSince: {}", passesUpdatedSince);
  		PKSerialNumbersOfPassesForDeviceResponse serialNumbersOfPassesForDevice = getSerialNumberOfPassesForDevice(deviceLibraryIdentifier,
  				passTypeIdentifier, passesUpdatedSince);
  		if (serialNumbersOfPassesForDevice == null || serialNumbersOfPassesForDevice.getSerialNumbers() == null) {
  			setStatusIntoResponse(Status.SUCCESS_NO_CONTENT, getResponse());
  			return null;
  		}
  		String responseJSONString;
  		try {
  			responseJSONString = jsonObjectMapper.writeValueAsString(serialNumbersOfPassesForDevice);
  			return new StringRepresentation(responseJSONString, MediaType.APPLICATION_JSON);
  		} catch (Exception e) {
  			LOGGER.error("Error when parsing response to JSON:", e);
  		}
  		setStatusIntoResponse(Status.SERVER_ERROR_INTERNAL, getResponse());
  		return null;
  	}
docs: /*
  GET request to webServiceURL/version/devices/{deviceLibraryIdentifier}/registrations/{passTypeIdentifier}?passesUpdatedSince=tag