kustomize, so there are a few backwards-incompatible changes, most of which are rare use cases, bug fixes with side effects, or things that have been deprecated for multiple releases already:
  
  - https://github.com/kubernetes-sigs/kustomize/pull/4911: Drop support for a very old, legacy style of patches. patches used to be allowed to be used as an alias for patchesStrategicMerge in kustomize v3. You now have to use patchesStrategicMerge explicitly, or update to the new syntax supported by patches....

   * -viper-config can be used to set also the options defined by command line flags
   * the default config file is "e2e.yaml/toml/json/..." and the test starts when no such config is found (as before) but if -viper-config is used, the config file must exist
   * -viper-config can be used to select a file with full path, with or without file suffix

- Some interfaces' signatures in the scheduler were updated: - PluginsRunner: used NodeInfo in `RunPreScorePlugins` and `RunScorePlugins`. - PreScorePlugin: used NodeInfo in `PreScore`. - Extender: used NodeInfo in `Filter` and `Prioritize`.
   ([#121954](https://github.com/kubernetes/kubernetes/pull/121954), [@AxeZhan](https://github.com/AxeZhan))

    3. Add function `GetNetworkResourceServicePrincipalToken` to fetch network resource service principal token, which will be used by Azure Network Resource (Load Balancer, Public IP, Route Table, Network Security Group and their sub level resources) Clients in this feature.
    4. Related unit tests.
  
  

* When specifying `--(kube|system)-reserved-cgroup`, with `--cgroup-driver=systemd`, it is now possible to use the fully qualified cgroupfs name (i.e. `/test-cgroup.slice`)....

    * for the kubelet is used, and is expected to be present in `/var/lib/kubelet/config.yaml`.
    * For runtime-detected, instance-specific configuration values, a environment file with
    * dynamically-generated flags at `kubeadm init` or `kubeadm join` run time is used.
    * Finally, if the user wants to override something specific for the kubelet that can't be done via

<a href="#Assignment_statements">assignment</a> or
explicit <a href="#Conversions">conversion</a>.
</p>

<pre>
chan T          // can be used to send and receive values of type T
chan&lt;- float64  // can only be used to send float64s
&lt;-chan int      // can only be used to receive ints
</pre>

<p>
The <code>&lt;-</code> operator associates with the leftmost <code>chan</code>
possible:
</p>

  - `alpha` support (guarded by the `ServiceAccountTokenPodNodeInfo` feature gate) for including the node name (and uid, if the node exists) as additional claims in service account tokens it issues which are bound to pods, and `authentication.kubernetes.io/node-name` and `authentication.kubernetes.io/node-uid` extra user info when the token is used to authenticate.

- Kubelet: a configuration file specified via `--config` is now loaded with strict deserialization,...

- The RuntimeClass API has been added. This feature is in alpha, and the RuntimeClass feature gate must be enabled in order to use it. The RuntimeClass API resource defines different classes of runtimes that may be used to run containers in the cluster. Pods can select a RuntimeClass to use via the RuntimeClassName field. ([#67737](https://github.com/kubernetes/kubernetes/pull/67737), [@tallclair](https://github.com/tallclair))