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
  static <V extends @Nullable Object, X extends Exception> V getChecked(

@GwtIncompatible
public class MockFutureListener implements Runnable {
  private final CountDownLatch countDownLatch;
  private final ListenableFuture<?> future;

  public MockFutureListener(ListenableFuture<?> future) {
    this.countDownLatch = new CountDownLatch(1);
    this.future = future;

    future.addListener(this, directExecutor());
  }

  @Override
  public void run() {
    countDownLatch.countDown();
  }

  /**

  static final OtherThrowable OTHER_THROWABLE = new OtherThrowable();
  static final Future<String> FAILED_FUTURE_OTHER_THROWABLE =
      immediateFailedFuture(OTHER_THROWABLE);
  static final Error ERROR = new Error("mymessage");
  static final Future<String> FAILED_FUTURE_ERROR = immediateFailedFuture(ERROR);
  static final Future<String> RUNTIME_EXCEPTION_FUTURE =
      UncheckedThrowingFuture.throwingRuntimeException(RUNTIME_EXCEPTION);

import java.util.concurrent.Future;
import org.jspecify.annotations.Nullable;

/** Emulation of Uninterruptibles in GWT. */
public final class Uninterruptibles {

  private Uninterruptibles() {}

  @CanIgnoreReturnValue
  public static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
      throws ExecutionException {
    try {
      return future.get();
    } catch (InterruptedException e) {

    assertFalse(future.isCancelled());

    ExecutorService executor = newSingleThreadExecutor();

    try {
      Future<Boolean> getResult = executor.submit(() -> future.get());

      // Release the future value.
      latch.countDown();

      assertTrue(getResult.get(10, SECONDS));
    } finally {
      executor.shutdownNow();
    }

    assertTrue(future.isDone());

   * Future} instances to be upgraded to {@code ListenableFuture} after the fact.
   */
  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
      Future<V> future) {
    if (future instanceof ListenableFuture) {
      return (ListenableFuture<V>) future;
    }
    return new ListenableFutureAdapter<>(future);
  }

  /**

        try {
          assertEquals("hello", data);
          future.complete(null);
        } catch (Exception e) {
          future.completeExceptionally(e);
        }
      }

      @Override
      public void onClosed(@NotNull EventSource eventSource) {
        future.completeExceptionally(new IllegalStateException("closed"));
      }

      @Override

   * completes. Cancelling the supplied future will also cancel the returned future, but cancelling
   * the returned future will have no effect on the supplied future.
   *
   * @since 15.0
   */
  public static <V extends @Nullable Object> ListenableFuture<V> nonCancellationPropagating(
      ListenableFuture<V> future) {
    if (future.isDone()) {
      return future;
    }

    assertTrue(future.isDone());
    assertTrue(future.isCancelled());

    assertThrows(CancellationException.class, () -> future.get());
  }

  public void testFailedFuture(@Nullable String message) throws InterruptedException {
    assertTrue(future.isDone());
    assertFalse(future.isCancelled());

    assertTrue(latch.await(5, SECONDS));
    assertTrue(future.isDone());
    assertFalse(future.isCancelled());

    SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object unused =
        new Object() {
          @SuppressWarnings({"removal", "Finalize"}) // b/260137033
          @Override
          protected void finalize() {
            future.set(null);
          }
        };
    unused = null; // Hint to the JIT that unused is unreachable
    GcFinalization.awaitDone(future);
    assertTrue(future.isDone());