}
    },
    ImmutableSorted {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        ImmutableSortedMap.Builder<Element, Element> builder = ImmutableSortedMap.naturalOrder();
        for (Element element : keys) {
          builder.put(element, element);
        }
        return builder.build();
      }
    };

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class SortedMapNavigationTester<K, V> extends AbstractMapTester<K, V> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private SortedMap<K, V> navigableMap;
  private Entry<K, V> a;
  private Entry<K, V> c;

  @Override
  public void setUp() throws Exception {

 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private final NavigableSet<E> delegate;

  public SafeTreeSet() {
    this(new TreeSet<E>());
  }

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class SortedMapNavigationTester<K, V> extends AbstractMapTester<K, V> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private SortedMap<K, V> navigableMap;
  private Entry<K, V> a;
  private Entry<K, V> c;

  @Override
  public void setUp() throws Exception {

 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeMap<K, V> implements Serializable, NavigableMap<K, V> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private final NavigableMap<K, V> delegate;

  public SafeTreeMap() {
    this(new TreeMap<K, V>());
  }

 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private final NavigableSet<E> delegate;

  public SafeTreeSet() {
    this(new TreeSet<E>());
  }

 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeMap<K, V> implements Serializable, NavigableMap<K, V> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private final NavigableMap<K, V> delegate;

  public SafeTreeMap() {
    this(new TreeMap<K, V>());
  }