- v1beta1
      - v1
    clientConfig:
      service:
        name: istiod
        namespace: istio-system
        path: /inject
        port: 443
    failurePolicy: Fail
    matchPolicy: Equivalent
    name: rev.namespace.sidecar-injector.istio.io
    namespaceSelector:
      matchLabels:
        istio.io/deactivated: never-match
    objectSelector:
      matchLabels:
        istio.io/deactivated: never-match

      - v1beta1
      - v1
    clientConfig:
      service:
        name: istiod
        namespace: istio-system
        path: /inject
        port: 443
    failurePolicy: Fail
    matchPolicy: Equivalent
    name: rev.namespace.sidecar-injector.istio.io
    namespaceSelector:
      matchExpressions:
        - key: istio.io/rev
          operator: In
          values:
            - default

   *
   * <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

   *
   * <p><b>{@code Stream} equivalent:</b> {@code Stream.empty()}.
   *
   * @since 20.0
   */
  public static <E extends @Nullable Object> FluentIterable<E> of() {
    return FluentIterable.from(Collections.<E>emptyList());
  }

  /**
   * Returns a fluent iterable containing the specified elements in order.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link java.util.stream.Stream#of(Object[])

   *   <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) {

  // 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

  // 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

       * TODO(cpovirk): consider no longer running these equivalent() tests on every Equivalence,
       * since the Equivalence base type now implements this logic itself
       */
      assertTrue(item + " must be inequivalent to null", !equivalence.equivalent(item, null));
      assertTrue("null must be inequivalent to " + item, !equivalence.equivalent(null, item));
      assertTrue(item + " must be equivalent to itself", equivalence.equivalent(item, item));

       * TODO(cpovirk): consider no longer running these equivalent() tests on every Equivalence,
       * since the Equivalence base type now implements this logic itself
       */
      assertTrue(item + " must be inequivalent to null", !equivalence.equivalent(item, null));
      assertTrue("null must be inequivalent to " + item, !equivalence.equivalent(null, item));
      assertTrue(item + " must be equivalent to itself", equivalence.equivalent(item, item));

  }

  protected void initMapWithNullKey() {
    resetMap(createArrayWithNullKey());
  }

  protected void initMapWithNullValue() {
    resetMap(createArrayWithNullValue());
  }

  /**
   * Equivalent to {@link #expectMissingKeys(Object[]) expectMissingKeys} {@code (null)} except that
   * the call to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *