*
       * ...except that it's possible for users to insert a string key with a non-string value, and
       * in that case, getProperty *will* return null.
       *
       * TODO(b/192002623): Handle that case: Either:
       *
       * - Skip non-string keys and values entirely, as proposed in the linked bug.
       *
       * - Throw ClassCastException instead of NullPointerException, as documented in the current

        if (this.equivalence.equals(that.equivalence)) {
          /*
           * We'll accept that as sufficient "proof" that either equivalence should be able to
           * handle either reference, so it's safe to circumvent compile-time type checking.
           */
          @SuppressWarnings("unchecked")
          Equivalence<Object> equivalence = (Equivalence<Object>) this.equivalence;

        if (this.equivalence.equals(that.equivalence)) {
          /*
           * We'll accept that as sufficient "proof" that either equivalence should be able to
           * handle either reference, so it's safe to circumvent compile-time type checking.
           */
          @SuppressWarnings("unchecked")
          Equivalence<Object> equivalence = (Equivalence<Object>) this.equivalence;

   * element is found, {@code defaultValue} will be returned from this method and the iterator will
   * be left exhausted: its {@code hasNext()} method will return {@code false}. Note that this can
   * usually be handled more naturally using {@code tryFind(iterator, predicate).or(defaultValue)}.
   *
   * @since 7.0
   */
  // For discussion of this signature, see the corresponding overload of *Iterables*.find.
  @CheckForNull