- The `client-go` dynamic client sets the header `Content-Type: application/json` by default ([#104327](https://github.com/kubernetes/kubernetes/pull/104327), [@sxllwx](https://github.com/sxllwx))

Additionally, these Kubernetes snapshot primitives act as basic building blocks that unlock the ability to develop advanced, enterprise-grade, storage administration features for Kubernetes: including application or cluster level backup solutions.

- KCM sets the upper-bound timeout limit for outgoing requests to 70s. Previously no timeout was set. Requests without explicit timeout might potentially hang forever and lead to starvation of the application. ([#99358](https://github.com/kubernetes/kubernetes/pull/99358), [@p0lyn0mial](https://github.com/p0lyn0mial)) [SIG API Machinery]

backup.

Also, please note:
- using `application/vnd.kubernetes.protobuf` as the media storage type for 1.6 is default but not required
- the ability to rollback to etcd2 can be preserved by setting the storage media type flag on `kube-apiserver`

  ```
  --storage-media-type application/json
  ```

  to continue to use `application/json` as the storage media type which can be changed to

- **Simplified User Experience**
  - Easier to get a cluster up and running (eg: `kubeadm`, intra-cluster bootstrapping)
  - Easier to understand a cluster (eg: API audit logs, server-based API defaults)
- **Stateful Application Support**
  - Enhanced persistence capabilities (eg: `StorageClasses`, new volume plugins)
  - New resources and scheduler features (eg: `ScheduledJob` resource, pod/node affinity/anti-affinity)
- **Cluster Federation**

### Experimental Features

* Init containers enable pod authors to perform tasks before their normal containers start. Each init container is started in order, and failing containers will prevent the application from starting. ([#23666](https://github.com/kubernetes/kubernetes/pull/23666), [@smarterclayton](https://github.com/smarterclayton))

### Other notable changes

- Fixed file permission issues that happened during update of Secret/ConfigMap/projected volume when fsGroup is used. The problem caused a race condition where application gets intermittent permission denied error when reading files that were just updated, before the correct permissions were applied. ([#114728](https://github.com/kubernetes/kubernetes/pull/114728), [@furkatgofurov7](https://github.com/furkatgofurov7))...