* instance. This method is guaranteed to only be called once.
   *
   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread pool
   * that sets the name of the thread to the {@linkplain #serviceName() service name}. Also, the
   * pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service

    AtomicReference<ScheduledExecutorService> executor = Atomics.newReference();
    AbstractScheduledService service =
        new AbstractScheduledService() {
          @Override
          protected void runOneIteration() throws Exception {}

          @Override
          protected ScheduledExecutorService executor() {
            executor.set(super.executor());

    AtomicReference<ScheduledExecutorService> executor = Atomics.newReference();
    AbstractScheduledService service =
        new AbstractScheduledService() {
          @Override
          protected void runOneIteration() throws Exception {}

          @Override
          protected ScheduledExecutorService executor() {
            executor.set(super.executor());

        ? (ListeningExecutorService) delegate
        : (delegate instanceof ScheduledExecutorService)
            ? new ScheduledListeningDecorator((ScheduledExecutorService) delegate)
            : new ListeningDecorator(delegate);
  }

  /**
   * Creates a {@link ScheduledExecutorService} whose {@code submit} and {@code invokeAll} methods

import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy;
import java.util.concurrent.TimeUnit;

/**

   * @since 33.4.0 (but since 28.0 in the JRE flavor)
   */
  @J2ktIncompatible
  @GwtIncompatible // ScheduledExecutorService
  @IgnoreJRERequirement // Users will use this only if they're already using Duration.
  public final FluentFuture<V> withTimeout(
      Duration timeout, ScheduledExecutorService scheduledExecutor) {
    return withTimeout(toNanosSaturated(timeout), NANOSECONDS, scheduledExecutor);
  }

  /**

import com.google.common.util.concurrent.ForwardingListenableFuture.SimpleForwardingListenableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeoutException;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;

/**

import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * A ScheduledExecutorService that executes all scheduled actions immediately in the calling thread.
 *
 * <p>See {@link TestingExecutors#sameThreadScheduledExecutor()} for a full list of constraints.
 *
 * @author John Sirois

import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * A ScheduledExecutorService that executes all scheduled actions immediately in the calling thread.
 *
 * <p>See {@link TestingExecutors#sameThreadScheduledExecutor()} for a full list of constraints.
 *
 * @author John Sirois

   */
  @J2ktIncompatible
  @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
  @IgnoreJRERequirement // Users will use this only if they're already using Duration.
  // TODO(cpovirk): Return ListenableScheduledFuture?
  public static <O extends @Nullable Object> ListenableFuture<O> scheduleAsync(
      AsyncCallable<O> callable, Duration delay, ScheduledExecutorService executorService) {