* @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 28.2
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submit(
      Callable<O> callable, Executor executor) {
    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    executor.execute(task);
    return task;
  }

  /**

  }

  @Override
  public <T extends @Nullable Object> List<Future<T>> invokeAll(
      Collection<? extends Callable<T>> tasks) throws InterruptedException {
    return delegate().invokeAll(tasks);
  }

  @Override
  public <T extends @Nullable Object> List<Future<T>> invokeAll(
      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
      throws InterruptedException {

import java.util.logging.Level;
import java.util.logging.Logger;
import org.checkerframework.checker.nullness.qual.Nullable;

/** Emulation for AbstractFuture in GWT. */
@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
@ElementTypesAreNonnullByDefault
public abstract class AbstractFuture<V extends @Nullable Object> extends InternalFutureFailureAccess
    implements ListenableFuture<V> {

    }

    @Override
    public @Nullable T lower(T e) {
      return standardLower(e);
    }

    @Override
    public @Nullable T floor(T e) {
      return standardFloor(e);
    }

    @Override
    public @Nullable T ceiling(T e) {
      return standardCeiling(e);
    }

    @Override
    public @Nullable T higher(T e) {
      return standardHigher(e);
    }

 */
@Experimental
@Immutable
@Provider
public interface Node {

    /**
     * @return artifact for this node
     */
    @Nullable
    Artifact getArtifact();

    /**
     * @return dependency for this node
     */
    @Nullable
    Dependency getDependency();

    /**
     * Gets the child nodes of this node.
     *
     * @return the child nodes of this node, never {@code null}
     */

   * @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 28.2
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submit(
      Callable<O> callable, Executor executor) {
    TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
    executor.execute(task);
    return task;
  }

  /**

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class Platform {
  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class Platform {

  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>

          <item index="4" class="java.lang.String" itemvalue="edu.umd.cs.findbugs.annotations.Nullable" />
          <item index="5" class="java.lang.String" itemvalue="io.reactivex.annotations.Nullable" />
          <item index="6" class="java.lang.String" itemvalue="io.reactivex.rxjava3.annotations.Nullable" />

    };
  }

  @Override
  public @Nullable Entry<K, V> firstEntry() {
    return delegate.firstEntry();
  }

  @Override
  public K firstKey() {
    return delegate.firstKey();
  }

  @Override
  public @Nullable Entry<K, V> floorEntry(K key) {
    return delegate.floorEntry(checkValid(key));
  }

  @Override
  public @Nullable K floorKey(K key) {