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

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

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

    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 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();

    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);

  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapExclusive() {
    assertFalse(navigableMap.tailMap(a.getKey(), false).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapInclusive() {
    assertTrue(navigableMap.tailMap(a.getKey(), true).containsKey(a.getKey()));
  }

  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapExclusive() {
    assertFalse(navigableMap.tailMap(a.getKey(), false).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapInclusive() {
    assertTrue(navigableMap.tailMap(a.getKey(), true).containsKey(a.getKey()));
  }

    extends AbstractImmutableSortedMapMapInterfaceTest<String, Integer> {
  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("a", 1, "b", 2, "c", 3, "d", 4, "e", 5).tailMap("b");
  }

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

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return 1;
  }

    extends AbstractImmutableSortedMapMapInterfaceTest<String, Integer> {
  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("a", 1, "b", 2, "c", 3, "d", 4, "e", 5).tailMap("b");
  }

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

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return 1;
  }

    assertFalse(navigableMap.headMap(a.getKey()).containsKey(a.getKey()));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testTailMapInclusive() {
    assertTrue(navigableMap.tailMap(a.getKey()).containsKey(a.getKey()));
  }

  public void testHeadMap() {
    List<Entry<K, V>> entries =
        copyToList(
            getSubjectGenerator()