@CanIgnoreReturnValue
  @ParametricNullness
  static <V extends @Nullable Object, X extends Exception> V getChecked(
      Future<V> future, Class<X> exceptionClass) throws X {
    return getChecked(bestGetCheckedTypeValidator(), future, exceptionClass);
  }

  /** Implementation of {@link Futures#getChecked(Future, Class)}. */
  @CanIgnoreReturnValue
  @VisibleForTesting
  @ParametricNullness

    InterruptibleFuture future = new InterruptibleFuture();
    assertTrue(future.cancel(false));
    assertTrue(future.isCancelled());
    assertTrue(future.isDone());
    assertFalse(future.wasInterrupted());
    assertFalse(future.interruptTaskWasCalled);
    CancellationException e = assertThrows(CancellationException.class, () -> future.get());
    assertThat(e).hasCauseThat().isNull();
  }

      Class<X> exceptionType,
      Function<? super X, ? extends V> fallback,
      Executor executor) {
    CatchingFuture<V, X> future = new CatchingFuture<>(input, exceptionType, fallback);
    input.addListener(future, rejectionPropagatingExecutor(executor, future));
    return future;
  }

  static <X extends Throwable, V extends @Nullable Object> ListenableFuture<V> create(
      ListenableFuture<? extends V> input,

 *       Future} is "completed" even if it is cancelled while its underlying work continues on a
 *       thread, an RPC, etc. The {@code Future} is also "completed" if it fails "early" -- for
 *       example, if the deadline expires on a {@code Future} returned from {@link
 *       Futures#withTimeout} while the {@code Future} it wraps continues its underlying work. So

  private static void assertSetAsynchronously(AbstractFuture<Integer> future) {
    assertCannotSet(future);
    assertPending(future);
  }

  private static void assertPending(AbstractFuture<Integer> future) {
    assertThat(future.isDone()).isFalse();
    assertThat(future.isCancelled()).isFalse();

    CountingRunnable listener = new CountingRunnable();
    future.addListener(listener, directExecutor());
    listener.assertNotRun();

  @CanIgnoreReturnValue
  protected boolean setFuture(ListenableFuture<? extends V> future) {
    checkNotNull(future);

    // If this future is already cancelled, cancel the delegate.
    // TODO(cpovirk): Should we do this at the end of the method, as in the server version?
    // TODO(cpovirk): Use maybePropagateCancellationTo?
    if (isCancelled()) {
      future.cancel(mayInterruptIfRunning);
    }

    super.releaseResources(reason);
    /*
     * If the output future is done, then it won't need to interrupt the task later, so it can clear
     * its reference to it.
     *
     * If the output future is *not* done, then the task field will be cleared after the task runs
     * or after the output future is done, whichever comes first.
     */
    if (reason == OUTPUT_FUTURE_DONE) {
      this.task = null;
    }
  }

  @Override

  /**
   * Sets the result of this {@code Future} to match the supplied input {@code Future} once the
   * supplied {@code Future} is done, unless this {@code Future} has already been cancelled or set
   * (including "set asynchronously," defined below).
   *
   * <p>If the supplied future is {@linkplain #isDone done} when this method is called and the call

import static com.google.common.util.concurrent.FuturesGetCheckedInputs.FAILED_FUTURE_ERROR;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.FAILED_FUTURE_OTHER_THROWABLE;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.FAILED_FUTURE_UNCHECKED_EXCEPTION;
import static com.google.common.util.concurrent.FuturesGetCheckedInputs.OTHER_THROWABLE;

  CollectionFuture(
      ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
      boolean allMustSucceed) {
    super(futures, allMustSucceed, true);

    List<@Nullable Present<V>> values =
        futures.isEmpty()
            ? Collections.<@Nullable Present<V>>emptyList()
            : Lists.<@Nullable Present<V>>newArrayListWithCapacity(futures.size());

    // Populate the results list with null initially.