*   <li>If {@code equivalent(x, y)} and {@code equivalent(y, z)} are both true, then {@code
   *       equivalent(x, z)} is also true (<i>transitive</i> property)
   * </ul>
   *
   * <p>Note that all calls to {@code equivalent(x, y)} are expected to return the same result as
   * long as neither {@code x} nor {@code y} is modified.
   */
  public final boolean equivalent(@CheckForNull T a, @CheckForNull T b) {
    if (a == b) {

   *   <li>If {@code equivalent(x, y)} and {@code equivalent(y, z)} are both true, then {@code
   *       equivalent(x, z)} is also true (<i>transitive</i> property)
   * </ul>
   *
   * <p>Note that all calls to {@code equivalent(x, y)} are expected to return the same result as
   * long as neither {@code x} nor {@code y} is modified.
   */
  public final boolean equivalent(@CheckForNull T a, @CheckForNull T b) {
    if (a == b) {

   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
   * {@code Optional.ofNullable}.
   */
  public static <T> Optional<T> fromNullable(@CheckForNull T nullableReference) {
    return (nullableReference == null) ? Optional.<T>absent() : new Present<T>(nullableReference);
  }

  /**
   * Returns the equivalent {@code com.google.common.base.Optional} value to the given {@code

  /**
   * Determines if the given iterable contains no elements.
   *
   * <p>There is no precise {@link Iterator} equivalent to this method, since one can only ask an
   * iterator whether it has any elements <i>remaining</i> (which one does using {@link
   * Iterator#hasNext}).
   *
   * <p><b>{@code Stream} equivalent:</b> {@code !stream.findAny().isPresent()}
   *
   * @return {@code true} if the iterable contains no elements

   * which is not the case for the {@code java.util} equivalent.
   */
  public abstract T or(T defaultValue);

  /**
   * Returns this {@code Optional} if it has a value present; {@code secondChoice} otherwise.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method has no equivalent in Java 8's

  // If this is specified and differs from the value in "kind", an equivalent match and conversion was performed.
  //
  // For example, if deployments can be modified via apps/v1 and apps/v1beta1, and a webhook registered a rule of
  // `apiGroups:["apps"], apiVersions:["v1"], resources: ["deployments"]` and `matchPolicy: Equivalent`,
  // an API request to apps/v1beta1 deployments would be converted and sent to the webhook

   * implicit).
   */
  protected Ordering() {}

  // Instance-based factories (and any static equivalents)

  /**
   * Returns the reverse of this ordering; the {@code Ordering} equivalent to {@link
   * Collections#reverseOrder(Comparator)}.
   *
   * <p><b>Java 8+ users:</b> Use {@code thisComparator.reversed()} instead.
   */

  // If this is specified and differs from the value in "kind", an equivalent match and conversion was performed.
  //
  // For example, if deployments can be modified via apps/v1 and apps/v1beta1, and a webhook registered a rule of
  // `apiGroups:["apps"], apiVersions:["v1"], resources: ["deployments"]` and `matchPolicy: Equivalent`,
  // an API request to apps/v1beta1 deployments would be converted and sent to the webhook

  }

  /**
   * Returns an immutable sorted set containing the given elements sorted by their natural ordering.
   * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
   * one specified is included.
   *
   * @throws NullPointerException if any element is null
   */

  }

  /**
   * Returns an immutable sorted set containing the given elements sorted by their natural ordering.
   * When multiple elements are equivalent according to {@link Comparable#compareTo}, only the first
   * one specified is included.
   *
   * @throws NullPointerException if any element is null
   */