* might strip UnsafeComparator entirely. (TODO(cpovirk): Are we confident that optimizers
         * aren't stripping UnsafeComparator today? Should we have Proguard configuration for it?)
         *
         * - if Unsafe is removed entirely from JDKs (or already absent in some unusual environment
         * today). TODO: b/392974826 - Check for the existence of Unsafe and its methods

    return (result == null) ? keySet = createKeySet() : result;
  }

  /*
   * This could have a good default implementation of `return new ImmutableKeySet<K, V>(this)`, but
   * ProGuard can't figure out how to eliminate that default when RegularImmutableMap overrides it.
   */
  abstract ImmutableSet<K> createKeySet();

  UnmodifiableIterator<K> keyIterator() {

      result.descendingSet = this;
    }
    return result;
  }

  // Most classes should implement this as new DescendingImmutableSortedSet<E>(this),
  // but we push down that implementation because ProGuard can't eliminate it even when it's always
  // overridden.
  @GwtIncompatible // NavigableSet
  abstract ImmutableSortedSet<E> createDescendingSet();

  @Override
  public Spliterator<E> spliterator() {

        | (b5 & 0xFFL) << 24
        | (b6 & 0xFFL) << 16
        | (b7 & 0xFFL) << 8
        | (b8 & 0xFFL);
  }

  /*
   * Moving asciiDigits into this static holder class lets ProGuard eliminate and inline the Longs
   * class.
   */
  static final class AsciiDigits {
    private AsciiDigits() {}

    private static final byte[] asciiDigits;

    static {

      result.descendingSet = this;
    }
    return result;
  }

  // Most classes should implement this as new DescendingImmutableSortedSet<E>(this),
  // but we push down that implementation because ProGuard can't eliminate it even when it's always
  // overridden.
  @GwtIncompatible // NavigableSet
  abstract ImmutableSortedSet<E> createDescendingSet();

  /**
   * @since 12.0
   */

  static <T extends @Nullable Object> UnmodifiableListIterator<T> emptyListIterator() {
    return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
  }

  /**
   * This is an enum singleton rather than an anonymous class so ProGuard can figure out it's only
   * referenced by emptyModifiableIterator().
   */
  private enum EmptyModifiableIterator implements Iterator<Object> {
    INSTANCE;

    @Override
    public boolean hasNext() {

  static <T extends @Nullable Object> UnmodifiableListIterator<T> emptyListIterator() {
    return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
  }

  /**
   * This is an enum singleton rather than an anonymous class so ProGuard can figure out it's only
   * referenced by emptyModifiableIterator().
   */
  private enum EmptyModifiableIterator implements Iterator<Object> {
    INSTANCE;

    @Override
    public boolean hasNext() {

    request itself.
 *  New: `Headers.Builder.addAll(Headers)`.
 *  New: `ResponseBody.create(MediaType, ByteString)`.
 *  New: Embed R8/ProGuard rules in the jar. These will be applied automatically by R8.
 *  Fix: Release the connection if `Authenticator` throws an exception.
 *  Fix: Change the declaration of `OkHttpClient.cache()` to return a `@Nullable Cache`. The return