@Override
    Object writeReplace() {
      return super.writeReplace();
    }
  }

  static final class KeySet<K> extends ImmutableSet<K> {
    private final transient ImmutableMap<K, ?> map;
    private final transient ImmutableList<K> list;

    KeySet(ImmutableMap<K, ?> map, ImmutableList<K> list) {
      this.map = map;
      this.list = list;
    }

    @Override

      return delegate;
    }

    @Override
    public Set<K> keySet() {
      return new ForwardingSet<K>() {
        @Override
        protected Set<K> delegate() {
          return delegate.keySet();
        }

        @Override
        public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

        @Override

  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithKeySetIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<K> iterator = getMap().keySet().iterator();
          getMap().clear();
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)

    return tailMap(fromKey, true);
  }

  @Override
  public NavigableSet<K> navigableKeySet() {
    return new Maps.NavigableKeySet<>(this);
  }

  @Override
  public Set<K> keySet() {
    return navigableKeySet();
  }

  @Override
  public NavigableSet<K> descendingKeySet() {
    return descendingMap().navigableKeySet();
  }

  @Override

      ImmutableSortedMap.Builder<String, Integer> builder = ImmutableSortedMap.naturalOrder();
      for (int i = 0; i < elements.length; i++) {
        builder.put(elements[i], i);
      }
      return builder.build().keySet().asList();
    }

    @Override
    public List<String> order(List<String> insertionOrder) {
      return Ordering.<String>natural().sortedCopy(insertionOrder);
    }
  }

    assertEquals(3, multimap().size());
    assertEquals(3, multimap().entries().size());
    assertEquals(3, multimap().keys().size());

    assertEquals(1, multimap().keySet().size());
    assertEquals(1, multimap().asMap().size());
  }

    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry((K) null, 2), Multisets.immutableEntry(k1(), 1));
  }

  public void testKeysElementSet() {
    assertEquals(multimap().keySet(), multimap().keys().elementSet());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeysRemove() {
    int original = multimap().keys().remove(k0(), 1);

      return emptySet();
    } else {
      return emptyList();
    }
  }

  @Override
  public void clear() {
    keySet().clear();
  }

  @Override
  Set<K> createKeySet() {
    return Sets.filter(unfiltered.keySet(), keyPredicate);
  }

  @Override
  public Collection<V> get(@ParametricNullness K key) {
    if (keyPredicate.apply(key)) {

      return emptySet();
    } else {
      return emptyList();
    }
  }

  @Override
  public void clear() {
    keySet().clear();
  }

  @Override
  Set<K> createKeySet() {
    return Sets.filter(unfiltered.keySet(), keyPredicate);
  }

  @Override
  public Collection<V> get(@ParametricNullness K key) {
    if (keyPredicate.apply(key)) {

 * order to {@code [key2, key1]}. The {@link #entries()} iterator returns mutable map entries, and
 * {@link #replaceValues} attempts to preserve iteration order as much as possible.
 *
 * <p>The collections returned by {@link #keySet()} and {@link #asMap()} iterate through the keys in
 * the order they were first added to the multimap. Similarly, {@link #get}, {@link #removeAll}, and