* #weakKeys} is specified, and {@link Equivalence#equals()} otherwise. The only place this is
   * used is in {@link Interners.WeakInterner}.
   */
  @CanIgnoreReturnValue
  @GwtIncompatible // To be supported
  MapMaker keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);

    BiPredicate<ImmutableSortedMap<String, Integer>, ImmutableSortedMap<String, Integer>>
        equivalence =
            Equivalence.equals()
                .onResultOf(ImmutableSortedMap<String, Integer>::comparator)
                .and(Equivalence.equals().onResultOf(map -> map.entrySet().asList()))
                .and(Equivalence.equals());
    ImmutableSortedMap<String, Integer> expected =

import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import org.jspecify.annotations.Nullable;

/**
 * Equivalence applied on functional result.
 *
 * @author Bob Lee
 * @since 10.0
 */
@GwtCompatible
final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import org.jspecify.annotations.Nullable;

/**
 * Equivalence applied on functional result.
 *
 * @author Bob Lee
 * @since 10.0
 */
@GwtCompatible
final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

   * #weakKeys} is specified, and {@link Equivalence#equals()} otherwise. The only place this is
   * used is in {@link Interners.WeakInterner}.
   */
  @CanIgnoreReturnValue
  @GwtIncompatible // To be supported
  MapMaker keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);

     */

    STRONG {
      @Override
      Equivalence<Object> defaultEquivalence() {
        return Equivalence.equals();
      }
    },

    SOFT {
      @Override
      Equivalence<Object> defaultEquivalence() {
        return Equivalence.identity();
      }
    },

    WEAK {
      @Override
      Equivalence<Object> defaultEquivalence() {
        return Equivalence.identity();

import java.util.Iterator;
import org.jspecify.annotations.Nullable;

@GwtCompatible
final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
    implements Serializable {
  final Equivalence<E> elementEquivalence;

  PairwiseEquivalence(Equivalence<E> elementEquivalence) {
    this.elementEquivalence = Preconditions.checkNotNull(elementEquivalence);
  }

  @Override

  }

  public void testToImmutableSet() {
    Collector<String, ?, ImmutableSet<String>> collector = toImmutableSet();
    Equivalence<ImmutableSet<String>> equivalence =
        Equivalence.equals().onResultOf(ImmutableSet::asList);
    CollectorTester.of(collector, equivalence)
        .expectCollects(ImmutableSet.of("a", "b", "c", "d"), "a", "b", "a", "c", "b", "b", "d");
  }

import java.util.Iterator;
import org.jspecify.annotations.Nullable;

@GwtCompatible
final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
    implements Serializable {
  final Equivalence<E> elementEquivalence;

  PairwiseEquivalence(Equivalence<E> elementEquivalence) {
    this.elementEquivalence = Preconditions.checkNotNull(elementEquivalence);
  }

  @Override

  @CanIgnoreReturnValue
  CacheBuilder<K, V> keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

  /**