* Make NodeController recognize deletion tombstones ([#34786](https://github.com/kubernetes/kubernetes/pull/34786), [@davidopp](https://github.com/davidopp))
* Delete all firewall rules (and optionally network) on GCE/GKE cluster teardown ([#34577](https://github.com/kubernetes/kubernetes/pull/34577), [@ixdy](https://github.com/ixdy))

- Both directory and block devices are now supported for local volume plugin FileSystem VolumeMode.  ([#63011](https://github.com/kubernetes/kubernetes/pull/63011), [@NickrenREN](https://github.com/NickrenREN))
- CSI NodePublish call can optionally contain information about the pod that requested the CSI volume. ([#67945](https://github.com/kubernetes/kubernetes/pull/67945), [@jsafrane](https://github.com/jsafrane))

  }

  private static final Function<Object, Optional<?>> NULLABLE_TO_OPTIONAL =
      new Function<Object, Optional<?>>() {
        @Override
        public Optional<?> apply(@Nullable Object obj) {
          return Optional.fromNullable(obj);
        }
      };

  private static final Function<Optional<?>, @Nullable Object> OPTIONAL_TO_NULLABLE =
      new Function<Optional<?>, @Nullable Object>() {
        @Override

- JWT authenticators specified via the `AuthenticationConfiguration.jwt` array can now optionally specify either the `controlplane` or `cluster` egress selector by setting the `issuer.egressSelectorType` field.  When unset, the prior behavior of using no egress selector is retained.  The StructuredAuthenticationConfigurationEgressSelector beta...

   * Predicates.notNull())}, static importing as necessary.
   *
   * <p><b>Note:</b> if {@code first} is represented as an {@link Optional}, this can be
   * accomplished with {@link Optional#or(Object) first.or(second)}. That approach also allows for
   * lazy evaluation of the fallback instance, using {@link Optional#or(Supplier)
   * first.or(supplier)}.
   *
   * <p><b>Java 9 users:</b> use {@code java.util.Objects.requireNonNullElse(first, second)}

#### Custom Resource Definitions (CRDs)
* [alpha] The CustomResourceDefinition API can now optionally
  [validate custom objects](https://kubernetes.io/docs/tasks/access-kubernetes-api/extend-api-custom-resource-definitions/#validation)
  based on a JSON schema provided in the CRD spec.

   * Predicates.notNull())}, static importing as necessary.
   *
   * <p><b>Note:</b> if {@code first} is represented as an {@link Optional}, this can be
   * accomplished with {@link Optional#or(Object) first.or(second)}. That approach also allows for
   * lazy evaluation of the fallback instance, using {@link Optional#or(Supplier)
   * first.or(supplier)}.
   *
   * <p><b>Java 9 users:</b> use {@code java.util.Objects.requireNonNullElse(first, second)}

- CustomResourceDefinitions added support for marking versions as deprecated by setting `spec.versions[*].deprecated` to `true`, and for optionally overriding the default deprecation warning with a `spec.versions[*].deprecationWarning` field. ([#92329](https://github.com/kubernetes/kubernetes/pull/92329), [@liggitt](https://github.com/liggitt)) [SIG API Machinery]

	* A new controller for managing DNS records is introduced which can be optionally disabled to enable third party components to manage DNS records for federated services. ([#45034](https://github.com/kubernetes/kubernetes/pull/45034), [@shashidharatd](https://github.com/shashidharatd))

  @Override
  public T get() {
    return reference;
  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    checkNotNull(secondChoice);
    return this;
  }

  @Override
  public T or(Supplier<? extends T> supplier) {