* turn, and does not create any threads of its own.
   *
   * <p>After execution begins on a thread from the {@code delegate} {@link Executor}, tasks are
   * polled and executed from a task queue until there are no more tasks. The thread will not be
   * released until there are no more tasks to run.
   *

     */
    WeakValueReference<K, V, E> copyFor(ReferenceQueue<V> queue, E entry);
  }

  /**
   * A dummy implementation of {@link InternalEntry}, solely for use in the type signature of {@link
   * #UNSET_WEAK_VALUE_REFERENCE} below.
   */
  static final class DummyInternalEntry
      implements InternalEntry<Object, Object, DummyInternalEntry> {

  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *

    waiter.awaitWaiting();
    PollingThread poller = new PollingThread(future);
    poller.start();
    PollingThread poller2 = new PollingThread(future);
    poller2.start();
    PollingThread poller3 = new PollingThread(future);
    poller3.start();
    poller.awaitInLoop();
    poller2.awaitInLoop();
    poller3.awaitInLoop();

    // The waiter queue should be {poller x 3}->waiter1
    waiter.interrupt();

  /**
   * Returns a fluent iterable that combines two iterables. The returned iterable has an iterator
   * that traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#concat}.

    waiter.awaitWaiting();
    PollingThread poller = new PollingThread(future);
    poller.start();
    PollingThread poller2 = new PollingThread(future);
    poller2.start();
    PollingThread poller3 = new PollingThread(future);
    poller3.start();
    poller.awaitInLoop();
    poller2.awaitInLoop();
    poller3.awaitInLoop();

    // The waiter queue should be {poller x 3}->waiter1
    waiter.interrupt();

    };
  }

  /**
   * Combines two iterators into a single iterator. The returned iterator iterates across the
   * elements in {@code a}, followed by the elements in {@code b}. The source iterators are not
   * polled until necessary.
   *
   * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
   * supports it.
   */
  public static <T extends @Nullable Object> Iterator<T> concat(

  }

  /**
   * Combines two iterables into a single iterable. The returned iterable has an iterator that
   * traverses the elements in {@code a}, followed by the elements in {@code b}. The source
   * iterators are not polled until necessary.
   *
   * <p>The returned iterable's iterator supports {@code remove()} when the corresponding input
   * iterator supports it.
   *

     * (never less than 1, never more than 2), depending on project packaging.
     * <p>
     * The list's first element is ALWAYS the project POM artifact. Presence of second element in the list depends
     * solely on the project packaging.
     *
     * @see #getPackaging()
     * @see #getPomArtifact()
     * @see #getMainArtifact()
     * @see org.apache.maven.api.services.ArtifactManager#getPath(Artifact)
     */

 *
 * <p>Subscribers should not, in general, throw. If they do, the EventBus will catch and log the
 * exception. This is rarely the right solution for error handling and should not be relied upon; it
 * is intended solely to help find problems during development.
 *
 * <p>The EventBus guarantees that it will not call a subscriber method from multiple threads
 * simultaneously, unless the method explicitly allows it by bearing the {@link