Mac mac = Mac.getInstance("HmacMD5");
        MessageDigest md = MessageDigest.getInstance("MD5");
        mac.init(key);
        byte[] dk = mac.doFinal(MD5_CONSTANT);
        try {
            // little endian
            md.update((byte) (ms_usage & 0xFF));
            md.update((byte) (ms_usage >> 8 & 0xFF));
            md.update((byte) (ms_usage >> 16 & 0xFF));
            md.update((byte) (ms_usage >> 24 & 0xFF));

Tu API casi siempre tiene que enviar un **response** body. Pero los clientes no necesariamente necesitan enviar **request bodies** todo el tiempo, a veces solo solicitan un path, quizás con algunos parámetros de query, pero no envían un body.

Para declarar un **request** body, usas modelos de <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> con todo su poder y beneficios.

/// info | Información

    void testReadParametersWireFormat() throws Exception {
        byte[] buffer = new byte[100];
        int expectedLength = 0x12345678;

        // Write length in little-endian format
        SMBUtil.writeInt4(expectedLength, buffer, 0);

        int result = response.readParametersWireFormat(buffer, 0, buffer.length);

        assertEquals(4, result);

    checkArgument(
        result == (int) result,
        "the total number of elements (%s) in the arrays must fit in an int",
        result);
    return (int) result;
  }

  /**
   * Returns a big-endian representation of {@code value} in a 2-element byte array; equivalent to
   * {@code ByteBuffer.allocate(2).putChar(value).array()}. For example, the input value {@code
   * '\\u5432'} would yield the byte array {@code {0x54, 0x32}}.

        System.arraycopy(label, 0, suffix, 0, label.length);
        // + 1 byte 0x00
        // + context
        System.arraycopy(context, 0, suffix, label.length + 1, context.length);
        // + 4 byte (== r bits) big endian encoding of L
        suffix[suffix.length - 1] = (byte) 128;

        final DerivationParameters param = new KDFCounterParameters(sessionKey, null /* prefix */, suffix /* suffix */, r /* r */);
        gen.init(param);

        assertTrue(infoString.contains("bytesPerSect=512"), "toString should contain bytesPerSect");
    }

    // Helper methods to write numbers to byte array in little-endian format.
    private void writeInt2(int val, byte[] dst, int dstIndex) {
        dst[dstIndex++] = (byte) val;
        dst[dstIndex++] = (byte) (val >> 8);
    }

        Type1Message type1 = new Type1Message(mockContext);
        byte[] messageBytes = type1.toByteArray();

        // Then
        assertTrue(messageBytes.length >= 12);
        // Message type should be 1 (little endian)
        assertEquals(1, messageBytes[8] & 0xFF);
        assertEquals(0, messageBytes[9] & 0xFF);
        assertEquals(0, messageBytes[10] & 0xFF);
        assertEquals(0, messageBytes[11] & 0xFF);
    }

/**
 * Unit tests for {@link HashCode}.
 *
 * @author Dimitris Andreou
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
public class HashCodeTest extends TestCase {
  // note: asInt(), asLong() are in little endian
  private static final ImmutableList<ExpectedHashCode> expectedHashCodes =
      ImmutableList.of(
          new ExpectedHashCode(
              new byte[] {
                (byte) 0xef, (byte) 0xcd, (byte) 0xab, (byte) 0x89,

        int bytesWritten = request.writeBytesWireFormat(buffer, offset);

        // Then
        assertEquals(4, bytesWritten, "Should write 4 bytes");
        // Check that structure size (4) is written as 2-byte little-endian
        assertEquals(4, buffer[offset] | (buffer[offset + 1] << 8), "Structure size should be 4");
        assertEquals(0, buffer[offset + 2], "Reserved bytes should be 0");

### Swagger UI y `examples` específicos de OpenAPI

Ahora, como Swagger UI no soportaba múltiples ejemplos de JSON Schema (a fecha de 2023-08-26), los usuarios no tenían una forma de mostrar múltiples ejemplos en los documentos.

Para resolver eso, FastAPI `0.103.0` **añadió soporte** para declarar el mismo viejo campo **específico de OpenAPI** `examples` con el nuevo parámetro `openapi_examples`. 🤓