return new SimpleForwardingSortedMap<>(
        new TreeMap<String, Integer>(Ordering.<String>natural().nullsFirst()));
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    SortedMap<String, Integer> sortedMap = makeEmptyMap();
    sortedMap.put("one", 1);
    sortedMap.put("two", 2);
    sortedMap.put("three", 3);
    return sortedMap;
  }

  @Override

  protected abstract SortedMap<K, V> makeEmptyMap() throws UnsupportedOperationException;

  @Override
  protected abstract SortedMap<K, V> makePopulatedMap() throws UnsupportedOperationException;

  @Override
  protected SortedMap<K, V> makeEitherMap() {
    try {
      return makePopulatedMap();
    } catch (UnsupportedOperationException e) {
      return makeEmptyMap();
    }
  }

  public void testTailMapWriteThrough() {

  protected abstract SortedMap<K, V> makeEmptyMap() throws UnsupportedOperationException;

  @Override
  protected abstract SortedMap<K, V> makePopulatedMap() throws UnsupportedOperationException;

  @Override
  protected SortedMap<K, V> makeEitherMap() {
    try {
      return makePopulatedMap();
    } catch (UnsupportedOperationException e) {
      return makeEmptyMap();
    }
  }

  public void testTailMapWriteThrough() {

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

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

  @Override

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

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

  @Override

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

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

  @Override

    return Multimaps.transformValues(
            ArrayListMultimap.<String, Integer>create(), Functions.<Integer>identity())
        .asMap();
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    ListMultimap<String, Integer> delegate = ArrayListMultimap.create();
    populate(delegate);
    return Multimaps.transformValues(delegate, Functions.<Integer>identity()).asMap();
  }

    RowSortedTable<String, Character, Integer> table = TreeBasedTable.create();
    return unmodifiableRowSortedTable(table);
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    RowSortedTable<String, Character, Integer> table = TreeBasedTable.create();
    table.put("one", 'a', 1);
    table.put("two", 'a', 2);
    table.put("three", 'a', 3);
    table.put("four", 'b', 4);

  Table<String, Character, Integer> makeTable() {
    Table<String, Character, Integer> table = HashBasedTable.create();
    return unmodifiableTable(table);
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    Table<String, Character, Integer> table = HashBasedTable.create();
    table.put("one", 'a', 1);
    table.put("two", 'a', 2);
    table.put("three", 'a', 3);
    table.put("four", 'b', 4);

  @Override
  protected Map<Integer, UnhashableObject> makeEmptyMap() {
    return ImmutableMap.of();
  }

  @Override
  protected Map<Integer, UnhashableObject> makePopulatedMap() {
    Unhashables unhashables = new Unhashables();
    return ImmutableMap.of(0, unhashables.e0(), 1, unhashables.e1(), 2, unhashables.e2());
  }

  @Override
  protected Integer getKeyNotInPopulatedMap() {