}

  /**
   * A sensible definition of {@link #tailMap(Object)} in terms of {@link #tailMap(Object,
   * boolean)}. If you override {@code tailMap(K, boolean)}, you may wish to override {@code
   * tailMap} to forward to this implementation.
   */
  protected SortedMap<K, V> standardTailMap(@ParametricNullness K fromKey) {
    return tailMap(fromKey, true);
  }

  }

  /**
   * A sensible definition of {@link #tailMap(Object)} in terms of {@link #tailMap(Object,
   * boolean)}. If you override {@code tailMap(K, boolean)}, you may wish to override {@code
   * tailMap} to forward to this implementation.
   */
  protected SortedMap<K, V> standardTailMap(@ParametricNullness K fromKey) {
    return tailMap(fromKey, true);
  }

    return headMap(key, true).lastEntry();
  }

  @Override
  public @Nullable Entry<K, V> ceilingEntry(@ParametricNullness K key) {
    return tailMap(key, true).firstEntry();
  }

  @Override
  public @Nullable Entry<K, V> higherEntry(@ParametricNullness K key) {
    return tailMap(key, false).firstEntry();
  }

  @Override
  public @Nullable K lowerKey(@ParametricNullness K key) {

    Iterator<Entry<K, V>> iterator = map.entrySet().iterator();
    Entry<K, V> firstEntry = iterator.next();
    Entry<K, V> secondEntry = iterator.next();
    K key = secondEntry.getKey();
    SortedMap<K, V> subMap = map.tailMap(key);
    V value = getValueNotInPopulatedMap();
    subMap.put(key, value);
    assertEquals(secondEntry.getValue(), value);
    assertEquals(map.get(key), value);

    Iterator<Entry<K, V>> iterator = map.entrySet().iterator();
    Entry<K, V> firstEntry = iterator.next();
    Entry<K, V> secondEntry = iterator.next();
    K key = secondEntry.getKey();
    SortedMap<K, V> subMap = map.tailMap(key);
    V value = getValueNotInPopulatedMap();
    subMap.put(key, value);
    assertEquals(secondEntry.getValue(), value);
    assertEquals(map.get(key), value);

  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
    return delegate().subMap(fromKey, toKey);
  }

  @Override
  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
    return delegate().tailMap(fromKey);
  }

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

    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> tailMap(K fromKey) {
    return tailMap(fromKey, true);
  }

  @Override
  public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    return new SafeTreeMap<>(delegate.tailMap(checkValid(fromKey), inclusive));
  }

  @Override
  public Collection<V> values() {
    return delegate.values();

    return headMap(key, true).lastEntry();
  }

  @Override
  public @Nullable Entry<K, V> ceilingEntry(@ParametricNullness K key) {
    return tailMap(key, true).firstEntry();
  }

  @Override
  public @Nullable Entry<K, V> higherEntry(@ParametricNullness K key) {
    return tailMap(key, false).firstEntry();
  }

  @Override
  public @Nullable K lowerKey(@ParametricNullness K key) {

        .inOrder();
    assertEquals(map.headMap("three", true), map.descendingMap().tailMap("three", true));
    assertThat(map.tailMap("three", false).entrySet()).contains(mapEntry("two", 3));
    assertThat(map.tailMap("three", true).lowerEntry("three")).isNull();
    assertThat(map.headMap("two", false).values()).containsExactly(3, 5).inOrder();

    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> tailMap(K fromKey) {
    return tailMap(fromKey, true);
  }

  @Override
  public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    return new SafeTreeMap<>(delegate.tailMap(checkValid(fromKey), inclusive));
  }

  @Override
  public Collection<V> values() {
    return delegate.values();