new ForwardingWrapperTester()
        .testForwarding(
            NavigableMap.class,
            new Function<NavigableMap, NavigableMap>() {
              @Override
              public NavigableMap apply(NavigableMap delegate) {
                return wrap(delegate);
              }
            });
  }

  public void testEquals() {
    NavigableMap<Integer, String> map1 = ImmutableSortedMap.of(1, "one");

    assertNull(navigableMap.lowerEntry(k0()));
    assertNull(navigableMap.lowerKey(k0()));
    assertNull(navigableMap.floorEntry(k0()));
    assertNull(navigableMap.floorKey(k0()));
    assertNull(navigableMap.ceilingEntry(k0()));
    assertNull(navigableMap.ceilingKey(k0()));
    assertNull(navigableMap.higherEntry(k0()));
    assertNull(navigableMap.higherKey(k0()));
  }

  @CollectionSize.Require(ZERO)

    assertNull(navigableMap.lowerEntry(k0()));
    assertNull(navigableMap.lowerKey(k0()));
    assertNull(navigableMap.floorEntry(k0()));
    assertNull(navigableMap.floorKey(k0()));
    assertNull(navigableMap.ceilingEntry(k0()));
    assertNull(navigableMap.ceilingKey(k0()));
    assertNull(navigableMap.higherEntry(k0()));
    assertNull(navigableMap.higherKey(k0()));
  }

  @CollectionSize.Require(ZERO)

        TestSortedMapGenerator<K, V> delegate, Bound to, Bound from) {
      super(delegate, to, from);
    }

    @Override
    NavigableMap<K, V> createSubMap(SortedMap<K, V> sortedMap, K firstExclusive, K lastExclusive) {
      NavigableMap<K, V> map = (NavigableMap<K, V>) sortedMap;
      if (from == Bound.NO_BOUND && to == Bound.INCLUSIVE) {
        return map.headMap(lastInclusive, true);

 *
 * @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>());
  }

   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
   * interface.
   *
   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
   */
  @Override
  public NavigableMap<K, Collection<V>> asMap() {
    return (NavigableMap<K, Collection<V>>) super.asMap();
  }

  /**

        TestSortedMapGenerator<K, V> delegate, Bound to, Bound from) {
      super(delegate, to, from);
    }

    @Override
    NavigableMap<K, V> createSubMap(SortedMap<K, V> sortedMap, K firstExclusive, K lastExclusive) {
      NavigableMap<K, V> map = (NavigableMap<K, V>) sortedMap;
      if (from == Bound.NO_BOUND && to == Bound.INCLUSIVE) {
        return map.headMap(lastInclusive, true);

import com.google.common.collect.Maps.IteratorBasedAbstractMap;
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedMap;
import org.jspecify.annotations.Nullable;

/**
 * Skeletal implementation of {@link NavigableMap}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible

 *
 * @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>());
  }

import com.google.common.collect.Maps.IteratorBasedAbstractMap;
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedMap;
import org.jspecify.annotations.Nullable;

/**
 * Skeletal implementation of {@link NavigableMap}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible