/**
   * Do interruptible work here - do not complete Futures here, as their listeners could be
   * interrupted.
   */
  @ParametricNullness
  abstract T runInterruptibly() throws Exception;

  /**
   * Any interruption that happens as a result of calling interruptTask will arrive before this
   * method is called. Complete Futures here.
   */

  @SuppressWarnings("unchecked")
  public static <T extends @Nullable Object> Collector<T, ?, T> onlyElement() {
    return (Collector) ONLY_ELEMENT;
  }

  /**
   * This atrocity is here to let us report several of the elements in the stream if there were more
   * than one, not just two.
   */
  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
  private static final class ToOptionalState {

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

  @SuppressWarnings("unchecked")
  public static <T extends @Nullable Object> Collector<T, ?, T> onlyElement() {
    return (Collector) ONLY_ELEMENT;
  }

  /**
   * This atrocity is here to let us report several of the elements in the stream if there were more
   * than one, not just two.
   */
  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
  private static final class ToOptionalState {

   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying
   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as

   * tasks would be called recursively. Here, we detect that the delegate executor is executing
   * inline, and maintain a queue to dispatch tasks iteratively. There is one instance of this class
   * per call to submit() or submitAsync(), and each instance supports only one call to execute().
   *
   * <p>This class would certainly be simpler and easier to reason about if it were built with

  public void testTimeoutOnGetWorksCorrectly() throws InterruptedException, ExecutionException {

    // The task thread waits for the latch, so we expect a timeout here.
    try {
      future.get(20, MILLISECONDS);
      fail("Should have timed out trying to get the value.");
    } catch (TimeoutException expected) {
    } finally {
      latch.countDown();
    }
  }

        } while (oldHead != Waiter.TOMBSTONE);
      }
      // re-read valueField, if we get here then we must have observed a TOMBSTONE while trying to
      // add a waiter.
      // requireNonNull is safe because valueField is always set before TOMBSTONE.
      return getDoneValue(requireNonNull(valueField));
    }
    // If we get here then we have remainingNanos < SPIN_THRESHOLD_NANOS and there is no node on the
    // waiters list

    AfterEnqueuedTasks,

    /** Resumes after all other tasks, including tasks enqueued while yielding. */
    AfterOtherTasks,
  }

  /** Returns the task that was started, or null if there were no tasks to start. */
  private fun startNextTask(): SerialTask? {
    taskRunner.assertLockHeld()

    val index = serialTaskQueue.indexOfFirst { it.isReady() }
    if (index == -1) return null

  /** Return type from "contains the following elements" assertions. */
  public interface Ordered {
    /**
     * Attests that the expected values must not just be present but must be present in the order
     * they were given.
     */
    void inOrder();
  }

  @IgnoreJRERequirement // *should* be redundant with the annotation on SpliteratorTester
  private abstract static class GeneralSpliterator<E extends @Nullable Object> {