}

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

    @Override
    public NavigableMap<K, Collection<V>> tailMap(
        @ParametricNullness K fromKey, boolean inclusive) {
      return new NavigableAsMap(sortedMap().tailMap(fromKey, inclusive));
    }
  }

  }

  @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()

    public SortedMap<C, V> headMap(C toKey) {
      checkArgument(rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, lowerBound, toKey);
    }

    @Override
    public SortedMap<C, V> tailMap(C fromKey) {
      checkArgument(rangeContains(checkNotNull(fromKey)));
      return new TreeRow(rowKey, fromKey, upperBound);
    }

    @Override
    public C firstKey() {
      updateBackingRowMapField();

    public SortedMap<C, V> headMap(C toKey) {
      checkArgument(rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, lowerBound, toKey);
    }

    @Override
    public SortedMap<C, V> tailMap(C fromKey) {
      checkArgument(rangeContains(checkNotNull(fromKey)));
      return new TreeRow(rowKey, fromKey, upperBound);
    }

    @Override
    public C firstKey() {
      updateBackingRowMapField();

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

      return standardHeadMap(toKey);
    }

    @Override
    public K lastKey() {
      return standardLastKey();
    }

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

  static class StandardLastEntryForwardingNavigableMap<K, V> extends ForwardingNavigableMap<K, V> {
    private final NavigableMap<K, V> backingMap;