### Extending Ingress with and replacing a deprecated annotation with IngressClass

In Kubernetes 1.18, there are two significant additions to Ingress: A new `pathType` field and a new `IngressClass` resource. The `pathType` field allows specifying how paths should be matched. In addition to the default `ImplementationSpecific` type, there are new `Exact` and `Prefix` path types. 

      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier

  - The built-in `system:aws-cloud-provider` cluster role is deprecated and will not be auto-created in a future release. Deployments using the AWS cloud provider should grant required permissions to the `aws-cloud-provider` service account in the...

      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
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v1beta1 PodDisruptionBudget handling of "strategic merge patch"-type API requests for the `selector` field. Prior to 1.21, these requests would merge `matchLabels` content and replace `matchExpressions` content. In 1.21, patch requests touching the `selector` field started replacing the entire selector. This is consistent with server-side apply and the v1 PodDisruptionBudget behavior, but should not have been changed for v1beta1. ([#108141](https://github.com/kubernetes/kubernetes/pull/108141), ...

- Fixed several bugs involving the IPFamily field when creating or updating services
  in clusters with the IPv6DualStack feature gate enabled.
  
  Beware that the behavior of the IPFamily field is strange and inconsistent and will
  likely be changed before the dual-stack feature goes GA. Users should treat the
  field as "write-only" for now and should not make any assumptions about a service

v1beta1 PodDisruptionBudget handling of `strategic merge patch`-type API requests for the `selector` field. Prior to 1.21, these requests would merge `matchLabels` content and replace `matchExpressions` content. In 1.21, patch requests touching the `selector` field started replacing the entire selector. This is consistent with server-side apply and the v1 PodDisruptionBudget behavior, but should not have been changed for v1beta1. ([#108138](https://github.com/kubernetes/kubernetes/pull/108138), ...

v1beta1 PodDisruptionBudget handling of "strategic merge patch"-type API requests for the `selector` field. Prior to 1.21, these requests would merge `matchLabels` content and replace `matchExpressions` content. In 1.21, patch requests touching the `selector` field started replacing the entire selector. This is consistent with server-side apply and the v1 PodDisruptionBudget behavior, but should not have been changed for v1beta1. ([#108139](https://github.com/kubernetes/kubernetes/pull/108139), ...

## Known Issues

- The `metadata.clusterName` field is completely removed. This should not have any user-visible impact. ([#109602](https://github.com/kubernetes/kubernetes/pull/109602), [@lavalamp](https://github.com/lavalamp))