}
    return hash;
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object instanceof PairwiseEquivalence) {
      @SuppressWarnings("unchecked")
      PairwiseEquivalence<Object, Object> that = (PairwiseEquivalence<Object, Object>) object;
      return this.elementEquivalence.equals(that.elementEquivalence);
    }

    return false;
  }

  @Override

    // Ideally, the returned equivalence would support Iterable<? extends T>. However,
    // the need for this is so rare that it's not worth making callers deal with the ugly wildcard.
    return new PairwiseEquivalence<>(this);
  }

  /**
   * Returns a predicate that evaluates to true if and only if the input is equivalent to {@code
   * target} according to this equivalence relation.
   *
   * @since 10.0
   */