* directly against {@code equals()} rather than through the {@code Equivalence}.
   */
  private final Equivalence<? super T> equivalence;

  private final String relationshipName;
  private final String hashName;
  private final ItemReporter itemReporter;
  private final List<ImmutableList<T>> groups = new ArrayList<>();

  RelationshipTester(
      Equivalence<? super T> equivalence,
      String relationshipName,
      String hashName,

       * since the Equivalence base type now implements this logic itself
       */
      assertTrue(item + " must be inequivalent to null", !equivalence.equivalent(item, null));
      assertTrue("null must be inequivalent to " + item, !equivalence.equivalent(null, item));
      assertTrue(item + " must be equivalent to itself", equivalence.equivalent(item, item));
      assertEquals(

   * directly against {@code equals()} rather than through the {@code Equivalence}.
   */
  private final Equivalence<? super T> equivalence;

  private final String relationshipName;
  private final String hashName;
  private final ItemReporter itemReporter;
  private final List<ImmutableList<T>> groups = new ArrayList<>();

  RelationshipTester(
      Equivalence<? super T> equivalence,
      String relationshipName,
      String hashName,

        .addEquivalenceGroup("a")
        .test();
  }

  public void testEquals() {
    new EqualsTester()
        .addEqualityGroup(Equivalence.equals(), Equivalence.equals())
        .addEqualityGroup(Equivalence.identity(), Equivalence.identity())
        .testEquals();
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() throws NoSuchMethodException {

        .addEquivalenceGroup("a")
        .test();
  }

  public void testEquals() {
    new EqualsTester()
        .addEqualityGroup(Equivalence.equals(), Equivalence.equals())
        .addEqualityGroup(Equivalence.identity(), Equivalence.identity())
        .testEquals();
  }

  @J2ktIncompatible
  @GwtIncompatible // NullPointerTester
  public void testNulls() throws NoSuchMethodException {

  // actually implement BiPredicate, and CollectorTests expects a BiPredicate.
  static <C, E extends @Nullable Object, R extends Iterable<E>>
      BiPredicate<C, C> pairwiseOnResultOf(Function<C, R> arg) {
    Equivalence<C> equivalence = Equivalence.equals().<E>pairwise().onResultOf(arg);
    return equivalence::equivalent;
  }

  @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());
  }

  /**

        toImmutableEnumMap(Entry::getKey, Entry::getValue);
    Equivalence<ImmutableMap<AnEnum, Integer>> equivalence =
        Equivalence.equals().<Entry<AnEnum, Integer>>pairwise().onResultOf(ImmutableMap::entrySet);
    CollectorTester.of(collector, equivalence)
        .expectCollects(
            ImmutableMap.of(AnEnum.A, 1, AnEnum.C, 2, AnEnum.E, 3),

import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertTrue;

import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Equivalence;
import com.google.common.collect.Iterables;
import com.google.common.testing.RelationshipTester.Item;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.ArrayList;
import java.util.List;

   * #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);