import com.google.common.base.Supplier;
import com.google.common.collect.Maps.IteratorBasedAbstractMap;
import com.google.common.collect.Maps.ViewCachingAbstractMap;
import com.google.common.collect.Sets.ImprovedAbstractSet;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.WeakOuter;
import java.io.Serializable;

import com.google.common.base.Supplier;
import com.google.common.collect.Maps.IteratorBasedAbstractMap;
import com.google.common.collect.Maps.ViewCachingAbstractMap;
import com.google.common.collect.Sets.ImprovedAbstractSet;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.WeakOuter;
import java.io.Serializable;

@GwtCompatible
public final class Sets {
  private Sets() {}

  /**
   * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll}
   * implementation.
   */
  abstract static class ImprovedAbstractSet<E extends @Nullable Object> extends AbstractSet<E> {
    @Override
    public boolean removeAll(Collection<?> c) {
      return removeAllImpl(this, c);
    }

    @Override

      @ParametricNullness
      E transform(Entry<E> entry) {
        return entry.getElement();
      }
    };
  }

  abstract static class ElementSet<E extends @Nullable Object> extends Sets.ImprovedAbstractSet<E> {
    abstract Multiset<E> multiset();

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

    @Override
    public boolean contains(@Nullable Object o) {

      @ParametricNullness
      E transform(Entry<E> entry) {
        return entry.getElement();
      }
    };
  }

  abstract static class ElementSet<E extends @Nullable Object> extends Sets.ImprovedAbstractSet<E> {
    abstract Multiset<E> multiset();

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

    @Override
    public boolean contains(@Nullable Object o) {

@GwtCompatible
public final class Sets {
  private Sets() {}

  /**
   * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll}
   * implementation.
   */
  abstract static class ImprovedAbstractSet<E extends @Nullable Object> extends AbstractSet<E> {
    @Override
    public boolean removeAll(Collection<?> c) {
      return removeAllImpl(this, c);
    }

    @Override

   * were added to the multimap.
   */
  @Override
  public Collection<V> values() {
    return super.values();
  }

  @VisibleForTesting
  @WeakOuter
  final class ValueSet extends Sets.ImprovedAbstractSet<V> {
    /*
     * We currently use a fixed load factor of 1.0, a bit higher than normal to reduce memory
     * consumption.
     */

    @ParametricNullness private final K key;

   * were added to the multimap.
   */
  @Override
  public Collection<V> values() {
    return super.values();
  }

  @VisibleForTesting
  @WeakOuter
  final class ValueSet extends Sets.ImprovedAbstractSet<V> {
    /*
     * We currently use a fixed load factor of 1.0, a bit higher than normal to reduce memory
     * consumption.
     */

    @ParametricNullness private final K key;

        return new ValueForKeyIterator(key, index);
      }
    };
  }

  @Override
  Set<K> createKeySet() {
    @WeakOuter
    final class KeySetImpl extends Sets.ImprovedAbstractSet<K> {
      @Override
      public int size() {
        return keyToKeyList.size();
      }

      @Override
      public Iterator<K> iterator() {
        return new DistinctKeyIterator();

        return new ValueForKeyIterator(key, index);
      }
    };
  }

  @Override
  Set<K> createKeySet() {
    @WeakOuter
    final class KeySetImpl extends Sets.ImprovedAbstractSet<K> {
      @Override
      public int size() {
        return keyToKeyList.size();
      }

      @Override
      public Iterator<K> iterator() {
        return new DistinctKeyIterator();