* 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

  private interface Electronics {}

  private interface ConsumerFacing<T> {}

  private static class Mall<T> {
    class Shop<ProductT> {}

    abstract class Retailer<ProductT> extends Shop<ProductT>
        implements Comparator<ProductT>, ConsumerFacing<ProductT> {}
  }

  private static class Outlet<T> extends Mall<T> {}

  private interface UseIterable<T extends Iterable<?>> {}

    // vol. 2, Knuth, 4.2.2, (16) to the two-variable case. We have two value series x_i and y_i.
    // We define the arithmetic means X_n = 1/n \sum_{i=1}^n x_i, and Y_n = 1/n \sum_{i=1}^n y_i.
    // We also define the sum of the products of the differences from the means
    //           C_n = \sum_{i=1}^n x_i y_i - n X_n Y_n
    // for all n >= 1. Then for all n > 1:
    //       C_{n-1} = \sum_{i=1}^{n-1} x_i y_i - (n-1) X_{n-1} Y_{n-1}

        A result(Collector<T, A, R> collector, Iterable<T> inputs);
  }

  /**
   * Verifies that the specified expected result is always produced by collecting the specified
   * inputs, regardless of how the elements are divided.
   */
  @SafeVarargs
  @CanIgnoreReturnValue

- X.509 client certificate authentication to the kube-apiserver now produces credential IDs (derived from the certificate's signature) , for use in audit logging. ([#125634](https://github.com/kubernetes/kubernetes/pull/125634), [@ahmedtd](https://github.com/ahmedtd)) [SIG API Machinery, Auth and Testing]

  private interface Electronics {}

  private interface ConsumerFacing<T> {}

  private static class Mall<T> {
    class Shop<ProductT> {}

    abstract class Retailer<ProductT> extends Shop<ProductT>
        implements Comparator<ProductT>, ConsumerFacing<ProductT> {}
  }

  private static class Outlet<T> extends Mall<T> {}

  private interface UseIterable<T extends Iterable<?>> {}

        DirFileEntryEnumIterator2 it = new DirFileEntryEnumIterator2(tree, parent, "*", null, 0);

        // Assert: enumeration is empty and close produced no extra close call (no fileId opened)
        assertFalse(it.hasNext(), "Empty listing should produce no elements");
        it.close();
        // No close should be sent because directory was never successfully opened

      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();

- Graduated the `LegacyServiceAccountTokenTracking` feature gate to Beta. The usage of auto-generated secret-based service account token now produces warnings by default, and relevant Secrets are labeled with a last-used timestamp (label key `kubernetes.io/legacy-token-last-used`). ([#114523](https://github.com/kubernetes/kubernetes/pull/114523), [@zshihang](https://github.com/zshihang)) [SIG...

 *   <li>It doesn't offer a way to wait for multiple events before taking action. For example, it
 *       doesn't offer a way to wait for multiple producers to all report that they're "ready," nor
 *       does it offer a way to batch multiple events from a single producer together.
 *   <li>It doesn't support backpressure and other features needed for resilience.
 *   <li>It doesn't provide much control of threading.