@ElementTypesAreNonnullByDefault
final class SingletonImmutableSet<E> extends ImmutableSet<E> {
  // We deliberately avoid caching the asList and hashCode here, to ensure that with
  // compressed oops, a SingletonImmutableSet packs all the way down to the optimal 16 bytes.

  final transient E element;

  SingletonImmutableSet(E element) {
    this.element = Preconditions.checkNotNull(element);
  }

   * Returns the string representation of an {@link InetAddress} suitable for inclusion in a URI.
   *
   * <p>For IPv4 addresses, this is identical to {@link InetAddress#getHostAddress()}, but for IPv6
   * addresses it compresses zeroes and surrounds the text with square brackets; for example {@code
   * "[2001:db8::1]"}.
   *
   * <p>Per section 3.2.2 of <a target="_parent"