* automate the process, often adding features like monitoring, debugging, and cancellation.
 * Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>The main purpose of {@link #addListener addListener} is to support this chaining. You will
 * rarely use it directly, in part because it does not provide direct access to the {@code Future}

 * automate the process, often adding features like monitoring, debugging, and cancellation.
 * Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>The main purpose of {@link #addListener addListener} is to support this chaining. You will
 * rarely use it directly, in part because it does not provide direct access to the {@code Future}

 * automate the process, often adding features like monitoring, debugging, and cancellation.
 * Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>The main purpose of {@link #addListener addListener} is to support this chaining. You will
 * rarely use it directly, in part because it does not provide direct access to the {@code Future}

 * use a framework. Frameworks automate the process, often adding features like monitoring,
 * debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <h4>{@link java.util.concurrent.CompletableFuture} / {@link java.util.concurrent.CompletionStage}
 * </h4>
 *

 * inserted by producers and extracted by consumers. Once created, the capacity cannot be increased.
 * Attempts to {@code put} an element into a full queue will result in the operation blocking;
 * attempts to {@code take} an element from an empty queue will similarly block.
 *
 * <p>This class supports an optional fairness policy for ordering waiting producer and consumer

 * monitoring, debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>
 *   <li><a href="https://dagger.dev/producers.html">Dagger Producers</a>
 * </ul>
 *
 * <p>If you do chain your operations manually, you may want to use {@link FluentFuture}.
 *
 * @author Kevin Bourrillion
 * @author Nishant Thakkar
 * @author Sven Mawson

      assertEquals(0, Queues.drain(q, ImmutableList.of(), 1, 10, MILLISECONDS));

      Producer producer = new Producer(q, 1);
      // producing one, will ask for two
      Future<?> producerThread = threadPool.submit(producer);
      producer.beganProducing.await();

      // make sure we time out
      Stopwatch timer = Stopwatch.createStarted();

        // When
        MessageDigest md4 = Crypto.getMD4();
        byte[] hash = md4.digest(data);

        // Then
        assertNotNull(hash);
        assertEquals(16, hash.length); // MD4 produces 128-bit hash
    }

    @Test
    @DisplayName("Should calculate MD5 hash correctly")
    void testMD5Hash() {
        // Given
        String input = "Hello World";
        byte[] data = input.getBytes();

            assertNull(nc.dc);
        }
    }

    @Nested
    @DisplayName("toString() Tests")
    class ToStringTests {

        @Test
        @DisplayName("toString with valid data produces expected format")
        void testToStringWithValidData() {
            byte[] challenge = new byte[] { (byte) 0x01, (byte) 0x02, (byte) 0x03, (byte) 0xFF };
            UniAddress dc = mock(UniAddress.class);

        assertTrue(result.contains("nextEntry="));
        assertTrue(result.contains("action="));
        assertTrue(result.contains("file=" + fileName));
        // Hexdump.toHexString produces 4-character padded uppercase hex
        String expectedHex = String.format("%04X", action);
        assertTrue(result.contains("0x" + expectedHex));
    }

    @Test