* @author Louis Wasserman
 */
@NullUnmarked
public class ForwardingNavigableMapTest extends TestCase {
  static class StandardImplForwardingNavigableMap<K, V> extends ForwardingNavigableMap<K, V> {
    private final NavigableMap<K, V> backingMap;

    StandardImplForwardingNavigableMap(NavigableMap<K, V> backingMap) {
      this.backingMap = backingMap;
    }

    @Override
    protected NavigableMap<K, V> delegate() {