return Maps.keyOrNull(higherEntry(key));
  }

  abstract Iterator<Entry<K, V>> descendingEntryIterator();

  @Override
  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
    return subMap(fromKey, true, toKey, false);
  }

  @Override
  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
    return headMap(toKey, false);
  }

  @Override

      } else if (from == Bound.EXCLUSIVE && to == Bound.EXCLUSIVE) {
        return map.subMap(firstExclusive, false, lastExclusive, false);
      } else if (from == Bound.EXCLUSIVE && to == Bound.INCLUSIVE) {
        return map.subMap(firstExclusive, false, lastInclusive, true);
      } else if (from == Bound.INCLUSIVE && to == Bound.INCLUSIVE) {
        return map.subMap(firstInclusive, true, lastInclusive, true);
      } else {

    table.put("b", "b", "x");
    table.put("b", "c", "y");
    table.put("b", "x", "n");
    table.put("a", "a", "d");
    table.row("b").subMap("c", "x").clear();
    assertEquals(table.row("b"), ImmutableMap.of("b", "x", "x", "n"));
    table.row("b").subMap("b", "y").clear();
    assertEquals(table.row("b"), ImmutableMap.of());
    assertFalse(table.backingMap.containsKey("b"));
  }

    return createMultimap().asMap().subMap("e", "p");
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    TreeMultimap<String, Integer> multimap = createMultimap();
    multimap.put("f", 1);
    multimap.put("f", 2);
    multimap.put("g", 3);
    multimap.put("h", 4);
    return multimap.asMap().subMap("e", "p");
  }

  @Override

    return createMultimap().asMap().subMap("e", "p");
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    TreeMultimap<String, Integer> multimap = createMultimap();
    multimap.put("f", 1);
    multimap.put("f", 2);
    multimap.put("g", 3);
    multimap.put("h", 4);
    return multimap.asMap().subMap("e", "p");
  }

  @Override

  }

  @Override
  @ParametricNullness
  public K lastKey() {
    return delegate().lastKey();
  }

  @Override
  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);
  }

  /**

    assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.headMap("emu"));

    assertEquals(ImmutableMap.of("banana", 6), filtered.subMap("banana", "dog"));
    assertEquals(ImmutableMap.of("dog", 3), filtered.subMap("cat", "emu"));

    assertEquals(ImmutableMap.of("dog", 3), filtered.tailMap("cat"));
    assertEquals(ImmutableMap.of("banana", 6, "dog", 3), filtered.tailMap("banana"));
  }

    TreeBasedTable<String, Integer, Character> table = makeTable();
    populateTable(table);
    return table.rowMap().subMap("b", "x");
  }

  @Override
  protected Map<String, Map<Integer, Character>> makeEmptyMap() {
    return makeTable().rowMap().subMap("b", "x");
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "z";
  }

   * This method returns a {@code ImmutableSortedMap}, consisting of the entries whose keys ranges
   * from {@code fromKey}, inclusive, to {@code toKey}, exclusive.
   *
   * <p>The {@link SortedMap#subMap} documentation states that a submap of a submap throws an {@link
   * IllegalArgumentException} if passed a {@code fromKey} less than an earlier {@code fromKey}.
   * However, this method doesn't throw an exception in that situation, but instead keeps the

    }

    @Override
    public Entry<K, V>[] createArray(int length) {
      return delegate.createArray(length);
    }
  }

  /** Two bounds (from and to) define how to build a subMap. */
  public enum Bound {
    INCLUSIVE,
    EXCLUSIVE,
    NO_BOUND;
  }

  public static class SortedSetSubsetTestSetGenerator<E extends @Nullable Object>
      implements TestSortedSetGenerator<E> {