Veamos todo esto con un ejemplo.

Imagina que desarrollas una aplicación que permite crear facturas.

Estas facturas tendrán un `id`, `title` (opcional), `customer` y `total`.

El usuario de tu API (un desarrollador externo) creará una factura en tu API con un request POST.

Luego tu API (imaginemos):

* Enviará la factura a algún cliente del desarrollador externo.
* Recogerá el dinero.

import jcifs.internal.util.SMBUtil;

/**
 * Represents the FILE_FS_SIZE_INFORMATION structure used to query file system size information.
 * This structure provides details about the total allocation units, free allocation units,
 * sectors per allocation unit, and bytes per sector for a file system volume.
 */
public class FileFsSizeInformation implements AllocInfo {

    }

    /**
     * Concatenates multiple byte arrays into a single array.
     */
    private static byte[] concat(byte[]... arrays) {
        int total = 0;
        for (byte[] a : arrays) {
            total += a.length;
        }
        byte[] res = new byte[total];
        int off = 0;
        for (byte[] a : arrays) {
            System.arraycopy(a, 0, res, off, a.length);
            off += a.length;
        }

import jcifs.internal.util.SMBUtil;

/**
 * Represents the SMB_INFO_ALLOCATION information level used in SMB transaction requests.
 * This structure provides allocation information for a file system including total units,
 * free units, sectors per allocation unit, and bytes per sector.
 */
public class SmbInfoAllocation implements AllocInfo {

    /**
     * Default constructor for SMB allocation information.
     */

	Available  uint64 // in bytes
	MaxUsedPct int    // Used disk percentage of most filled disk, rounded down.
}

// TotalAvailable - total available space
func (p serverPoolsAvailableSpace) TotalAvailable() uint64 {
	total := uint64(0)
	for _, z := range p {
		total += z.Available
	}
	return total
}

// FilterMaxUsed will filter out any pools that has used percent bigger than max,

  /** True if this web socket failed and the listener has been notified. */
  private var failed = false

  /** Total number of pings sent by this web socket. */
  private var sentPingCount = 0

  /** Total number of pings received by this web socket. */
  private var receivedPingCount = 0

  /** Total number of pongs received by this web socket. */
  private var receivedPongCount = 0

    // GET /api/admin/log/files
    @Execute
    public JsonResponse<ApiResult> files() {
        final List<Map<String, Object>> list = getLogFileItems();
        return asJson(new ApiResult.ApiLogFilesResponse().files(list).total(list.size()).status(ApiResult.Status.OK).result());
    }

    /**
     * Downloads a specific log file by ID.
     *
     * @param id the base64-encoded filename of the log file to download

)

// bucketMeasurement captures the bandwidth details for one bucket
type bucketMeasurement struct {
	lock                 sync.Mutex
	bytesSinceLastWindow uint64    // Total bytes since last window was processed
	startTime            time.Time // Start time for window
	expMovingAvg         float64   // Previously calculate sliding window
}

	// Completed size in bytes
	ReplicatedSize int64 `json:"completedReplicationSize"`
	// Failed size in bytes
	FailedSize int64 `json:"failedReplicationSize"`
	// Total number of failed operations
	FailedCount int64 `json:"failedReplicationCount"`
	// Total number of failed operations
	ReplicatedCount int64 `json:"replicationCount"`
	// Last bucket/object replicated.
	Bucket string `json:"bucket,omitempty"`

func isReplicated(cntReplicated, total int, valSet set.StringSet) bool {
	if cntReplicated > 0 && cntReplicated < total {
		return false
	}
	if len(valSet) > 1 {
		// mismatch - one or more sites has differing tags/policy
		return false
	}
	return true
}

// isIAMPolicyReplicated returns true if count of replicated IAM policies matches total
// number of sites and IAM policies are identical.