*
 * @since 26.0
 */
@J2ktIncompatible
@GwtIncompatible
public final class ExecutionSequencer {

  private ExecutionSequencer() {}

  /** Creates a new instance. */
  public static ExecutionSequencer create() {
    return new ExecutionSequencer();
  }

  /** This reference acts as a pointer tracking the head of a linked list of ListenableFutures. */

import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/** Tests for {@link ExecutionSequencer} */
@NullUnmarked
public class ExecutionSequencerTest extends TestCase {

  ExecutorService executor;

  private ExecutionSequencer serializer;
  private SettableFuture<@Nullable Void> firstFuture;
  private TestCallable firstCallable;

  @Override