MockExecutor mock = new MockExecutor();
      TestExecutor testExecutor = new TestExecutor(mock);
      Future<?> f = testExecutor.submit(doNothing());
      mock.assertLastMethodCalled("submit");
      f.get();
    }
    {
      MockExecutor mock = new MockExecutor();
      TestExecutor testExecutor = new TestExecutor(mock);
      Future<String> f = testExecutor.submit(doNothing(), RESULT_VALUE);
      mock.assertLastMethodCalled("submit");

  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(

    /**
     * Contains the most recently submitted {@code Future}, which may be cancelled or updated,
     * always under a lock.
     */
    private static final class SupplantableFuture implements Cancellable {
      private final ReentrantLock lock;

      @GuardedBy("lock")
      private Future<@Nullable Void> currentFuture;

      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
        this.lock = lock;

    delegate().execute(command);
  }

  @Override
  public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
    return delegate().submit(task);
  }

  @Override
  public Future<?> submit(Runnable task) {
    return delegate().submit(task);
  }

  @Override
  public <T extends @Nullable Object> Future<T> submit(
      Runnable task, @ParametricNullness T result) {

        TestHandleReconnector testReconnector = new TestHandleReconnector(mockManager, true);

        CompletableFuture<HandleInfo> future = testReconnector.reconnectHandle("/test/file.txt", new IOException("Network error"));

        HandleInfo result = future.get();
        assertNotNull(result);
        assertEquals(testHandle, result);

        verify(mockManager).completeReconnect("/test/file.txt", true);
    }

 * result.
 *
 * @since 20.0
 */
@FunctionalInterface
@GwtCompatible
public interface AsyncCallable<V extends @Nullable Object> {
  /**
   * Computes a result {@code Future}. The output {@code Future} need not be {@linkplain
   * Future#isDone done}, making {@code AsyncCallable} suitable for asynchronous derivations.
   *
   * <p>Throwing an exception from this method is equivalent to returning a failing {@link

import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
 * it is invoked using this executor once the future's computation is {@linkplain Future#isDone()

        try {
            Future<List<FileNotifyInformation>> future = executor.submit(() -> blockingHandle.watch());

            // Verify timeout occurs
            assertThrows(TimeoutException.class, () -> {
                future.get(100, TimeUnit.MILLISECONDS);
            });

            // Cancel the future
            future.cancel(true);
        } finally {

import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
 * it is invoked using this executor once the future's computation is {@linkplain Future#isDone()

        /**
         * Gets the future for asynchronous notification completion
         * @return the notification future
         */
        public CompletableFuture<Void> getNotificationFuture() {
            return notificationFuture;
        }

        /**
         * Sets the future for asynchronous notification completion
         * @param future the notification future to set
         */