return Iterators.pollNext(descendingMap().entrySet().iterator());
  }

  @Override
  public NavigableMap<K, V> descendingMap() {
    return delegate().descendingMap();
  }

  /**
   * A sensible implementation of {@link NavigableMap#descendingMap} in terms of the methods of this
   * {@code NavigableMap}. In many cases, you may wish to override {@link

    return Iterators.pollNext(descendingMap().entrySet().iterator());
  }

  @Override
  public NavigableMap<K, V> descendingMap() {
    return delegate().descendingMap();
  }

  /**
   * A sensible implementation of {@link NavigableMap#descendingMap} in terms of the methods of this
   * {@code NavigableMap}. In many cases, you may wish to override {@link

    suite.addTest(
        NavigableMapTestSuiteBuilder.using(
                new TestStringSortedMapGenerator() {
                  @Override
                  protected NavigableMap<String, String> create(Entry<String, String>[] entries) {
                    NavigableMap<String, String> map = new SafeTreeMap<>();
                    putEntries(map, entries);
                    map.put("banana", "toast");

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

   * @since 12.0
   */
  @GwtIncompatible // NavigableMap
  public static <K extends @Nullable Object, V extends @Nullable Object>
      NavigableMap<K, V> unmodifiableNavigableMap(NavigableMap<K, ? extends V> map) {
    checkNotNull(map);
    if (map instanceof UnmodifiableNavigableMap) {
      @SuppressWarnings("unchecked") // covariant
      NavigableMap<K, V> result = (NavigableMap<K, V>) map;
      return result;
    } else {

   * @since 12.0
   */
  @GwtIncompatible // NavigableMap
  public static <K extends @Nullable Object, V extends @Nullable Object>
      NavigableMap<K, V> unmodifiableNavigableMap(NavigableMap<K, ? extends V> map) {
    checkNotNull(map);
    if (map instanceof UnmodifiableNavigableMap) {
      @SuppressWarnings("unchecked") // covariant
      NavigableMap<K, V> result = (NavigableMap<K, V>) map;
      return result;
    } else {

  }

  @GwtIncompatible // NavigableMap
  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(
      NavigableMap<K, V> navigableMap) {
    return navigableMap(navigableMap, null);
  }

  @GwtIncompatible // NavigableMap
  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(

  protected SortedMap<String, Integer> makePopulatedMap() {
    NavigableMap<String, Integer> map = new SafeTreeMap<>();
    map.put("one", 1);
    map.put("two", 2);
    map.put("three", 3);
    return SerializableTester.reserialize(map);
  }

  @Override
  protected SortedMap<String, Integer> makeEmptyMap() throws UnsupportedOperationException {
    NavigableMap<String, Integer> map = new SafeTreeMap<>();