}

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

  @Override
  public SortedSet<K> keySet() {
    return (SortedSet<K>) super.keySet();
  }

  @Override
  Set<K> createKeySet() {
    return createMaybeNavigableKeySet();
  }

                        ArrayTable.create(rowKeys, columnKeys);
                    populateForRowKeySet(table, elements);
                    return table.column(1).keySet();
                  }
                })
            .named("ArrayTable.column.keySet")
            .withFeatures(
                CollectionSize.ONE,
                CollectionSize.SEVERAL,
                CollectionFeature.KNOWN_ORDER,

    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeySetClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().keySet().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testValuesClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();

    assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Sets.newTreeSet()));
    // Before JDK6 (including under GWT), the TreeMap keySet is a plain Set.
    if (Maps.newTreeMap().keySet() instanceof SortedSet) {
      assertTrue(SortedIterables.hasSameComparator(Ordering.natural(), Maps.newTreeMap().keySet()));
    }
    assertTrue(
        SortedIterables.hasSameComparator(

    for (K key : multimap().keySet()) {
      SortedSet<V> valueSet = (SortedSet<V>) multimap().asMap().get(key);
      assertEquals(multimap().valueComparator(), valueSet.comparator());
    }
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testAsMapRemoveImplementsSortedSet() {
    List<K> keys = new ArrayList<>(multimap().keySet());
    for (K key : keys) {
      resetCollection();

import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import java.util.Spliterator;
import java.util.function.Consumer;
import javax.annotation.CheckForNull;

/**
 * {@code keySet()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

    assertTrue(multimap().containsKey(k0()));
  }

  public void testContainsKeyNo() {
    assertFalse(multimap().containsKey(k3()));
  }

  public void testContainsKeysFromKeySet() {
    for (K k : multimap().keySet()) {
      assertTrue(multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithGet() {
    for (K k : sampleKeys()) {
      assertEquals(!multimap().get(k).isEmpty(), multimap().containsKey(k));

    assertTrue(multimap().containsKey(k0()));
  }

  public void testContainsKeyNo() {
    assertFalse(multimap().containsKey(k3()));
  }

  public void testContainsKeysFromKeySet() {
    for (K k : multimap().keySet()) {
      assertTrue(multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithGet() {
    for (K k : sampleKeys()) {
      assertEquals(!multimap().get(k).isEmpty(), multimap().containsKey(k));

  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutPresentKeyPropagatesToGet() {
    List<K> keys = Helpers.copyToList(multimap().keySet());
    for (K key : keys) {
      resetContainer();

      int size = getNumElements();

      Collection<V> collection = multimap().get(key);

                    }
                    return multimap.keySet();
                  }

                  @Override
                  public List<String> order(List<String> insertionOrder) {
                    return Ordering.natural().nullsFirst().sortedCopy(insertionOrder);
                  }
                })
            .named("TreeMultimap.keySet")
            .withFeatures(