private class SortedAsMap extends AsMap implements SortedMap<K, Collection<V>> {
    SortedAsMap(SortedMap<K, Collection<V>> submap) {
      super(submap);
    }

    SortedMap<K, Collection<V>> sortedMap() {
      return (SortedMap<K, Collection<V>>) submap;
    }

    @Override
    @CheckForNull
    public Comparator<? super K> comparator() {
      return sortedMap().comparator();
    }

  @Override
  protected SortedMap<String, Integer> makeEmptyMap() {
    return new SimpleForwardingSortedMap<>(
        new TreeMap<String, Integer>(Ordering.<String>natural().nullsFirst()));
  }

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

    extends AbstractSortedSetMultimap<K, V> {

  AbstractSortedKeySortedSetMultimap(SortedMap<K, Collection<V>> map) {
    super(map);
  }

  @Override
  public SortedMap<K, Collection<V>> asMap() {
    return (SortedMap<K, Collection<V>>) super.asMap();
  }

  @Override
  SortedMap<K, Collection<V>> backingMap() {
    return (SortedMap<K, Collection<V>>) super.backingMap();
  }

  @Override

    extends ForwardingMap<K, V> implements SortedMap<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingSortedMap() {}

  @Override
  protected abstract SortedMap<K, V> delegate();

  @Override
  @CheckForNull
  public Comparator<? super K> comparator() {

    extends AbstractSortedSetMultimap<K, V> {

  AbstractSortedKeySortedSetMultimap(SortedMap<K, Collection<V>> map) {
    super(map);
  }

  @Override
  public SortedMap<K, Collection<V>> asMap() {
    return (SortedMap<K, Collection<V>>) super.asMap();
  }

  @Override
  SortedMap<K, Collection<V>> backingMap() {
    return (SortedMap<K, Collection<V>>) super.backingMap();
  }

  @Override

import com.google.common.annotations.GwtCompatible;
import java.util.SortedMap;

@GwtCompatible
@ElementTypesAreNonnullByDefault
public class FilteredSortedMapTest extends AbstractFilteredMapTest {
  @Override
  SortedMap<String, Integer> createUnfiltered() {
    return Maps.newTreeMap();
  }

  public void testFirstAndLastKeyFilteredMap() {
    SortedMap<String, Integer> unfiltered = createUnfiltered();

    extends MapDifference<K, V> {

  @Override
  SortedMap<K, V> entriesOnlyOnLeft();

  @Override
  SortedMap<K, V> entriesOnlyOnRight();

  @Override
  SortedMap<K, V> entriesInCommon();

  @Override
  SortedMap<K, ValueDifference<V>> entriesDiffering();

    suite.addTest(
        SortedMapTestSuiteBuilder.using(
                new TestStringSortedMapGenerator() {
                  @Override
                  protected SortedMap<String, String> create(Entry<String, String>[] entries) {
                    SortedMap<String, String> map = new NonNavigableSortedMap();
                    putEntries(map, entries);
                    map.putAll(ENTRIES_TO_FILTER);

    suite.addTest(
        SortedMapTestSuiteBuilder.using(
                new TestStringSortedMapGenerator() {
                  @Override
                  protected SortedMap<String, String> create(Entry<String, String>[] entries) {
                    SortedMap<String, String> map = new NonNavigableSortedMap();
                    putEntries(map, entries);
                    map.putAll(ENTRIES_TO_FILTER);

    return orderEntriesByKey(insertionOrder);
  }

  @Override
  protected abstract SortedMap<String, String> create(Entry<String, String>[] entries);

  @Override
  public SortedMap<String, String> create(Object... entries) {
    return (SortedMap<String, String>) super.create(entries);
  }