- OpenAPI spec now correctly marks delete request's body parameter as optional ([#70032](https://github.com/kubernetes/kubernetes/pull/70032), [@iamneha](https://github.com/iamneha))

  * Fix the bug where StartedAt time is not reported for exited containers. ([#45977](https://github.com/kubernetes/kubernetes/pull/45977), [@yujuhong](https://github.com/yujuhong))

* Changes/deprecations

  * Marks the Kubelet's `--master-service-namespace` flag deprecated ([#44250](https://github.com/kubernetes/kubernetes/pull/44250), [@mtaufen](https://github.com/mtaufen))

- Added a redundant process to remove tracking finalizers from Pods that belong to Jobs. The process kicks in after the control plane marks a Job as finished. ([#119944](https://github.com/kubernetes/kubernetes/pull/119944), [@Sharpz7](https://github.com/Sharpz7))

- **Admission webhooks:** Admission webhooks are in widespread use as a Kubernetes extensibility mechanism and have been available in beta since the 1.9 release. The 1.16 release marks the graduation of admission webhooks to general availability (GA).

- Kubelet now detects terminal CSI volume mount failures due to exceeded attachment limits on the node and marks the stateful pod as Failed, allowing its controller to recreate it. This prevents pods from getting stuck indefinitely in the `ContainerCreating` state. ([#132933](https://github.com/kubernetes/kubernetes/pull/132933), [@torredil](https://github.com/torredil))...