@Override
    public @Nullable K higherKey(@ParametricNullness K key) {
      return fromMap().higherKey(key);
    }

    @Override
    public @Nullable Entry<K, V2> lastEntry() {
      return transformEntry(fromMap().lastEntry());
    }

    @Override
    public @Nullable Entry<K, V2> lowerEntry(@ParametricNullness K key) {
      return transformEntry(fromMap().lowerEntry(key));
    }

    assertNull(navigableMap.higherEntry(k0()));
    assertNull(navigableMap.higherKey(k0()));
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapLast() {
    assertNull(navigableMap.lastEntry());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testEmptyMapPollLast() {
    assertNull(navigableMap.pollLastEntry());
  }

    assertNull(navigableMap.higherEntry(k0()));
    assertNull(navigableMap.higherKey(k0()));
  }

  @CollectionSize.Require(ZERO)
  public void testEmptyMapLast() {
    assertNull(navigableMap.lastEntry());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testEmptyMapPollLast() {
    assertNull(navigableMap.pollLastEntry());
  }

     * @param map the sequenced map
     * @return the last entry, or null if the map is empty
     * @since Java 21
     */
    public static <K, V> Map.Entry<K, V> lastEntry(final SequencedMap<K, V> map) {
        return map.isEmpty() ? null : map.lastEntry();
    }

    /**
     * Returns a reversed view of a sequenced map.
     *
     * @param <K> the key type
     * @param <V> the value type

    {
      Entry<Integer, String> entry = unmod.firstEntry();
      assertThrows(UnsupportedOperationException.class, () -> entry.setValue("four"));
    }
    {
      Entry<Integer, String> entry = unmod.lastEntry();
      assertThrows(UnsupportedOperationException.class, () -> entry.setValue("four"));
    }
    {
      @SuppressWarnings("unchecked")