*
 * @author Louis Wasserman
 */
@NullUnmarked
public class ForwardingNavigableSetTest extends TestCase {
  static class StandardImplForwardingNavigableSet<T> extends ForwardingNavigableSet<T> {
    private final NavigableSet<T> backingSet;

    StandardImplForwardingNavigableSet(NavigableSet<T> backingSet) {
      this.backingSet = backingSet;
    }

    @Override
    protected NavigableSet<T> delegate() {