where <code>P</code> is a type parameter and <code>C</code>
its corresponding constraint, the unification rules are bit
more complicated:
</p>

<ul>
<li>
	If <code>C</code> has a <a href="#Core_types">core type</a>
	<code>core(C)</code>
	and <code>P</code> has a known type argument <code>A</code>,
	<code>core(C)</code> and <code>A</code> must unify loosely.
	If <code>P</code> does not have a known type argument

  // More info: https://kubernetes.io/docs/concepts/storage/volumes#awselasticblockstore
  optional string volumeID = 1;

  // fsType is the filesystem type of the volume that you want to mount.
  // Tip: Ensure that the filesystem type is supported by the host operating system.
  // Examples: "ext4", "xfs", "ntfs". Implicitly inferred to be "ext4" if unspecified.

*   deviceplugin has been extended to more gracefully handle the full device plugin lifecycle, including: ([#55088](https://github.com/kubernetes/kubernetes/pull/55088),[ @jiayingz](https://github.com/jiayingz))
    *   Kubelet now uses an explicit cm.GetDevicePluginResourceCapacity() function that makes it possible to more accurately determine what resources are inactive and return a more accurate view of available resources.

* `kubectl wait` is a new command that allows waiting for one or more resources to be deleted or to reach a specific condition. It adds a `kubectl wait --for=[delete|condition=condition-name] resource/string` command. ([#64034](https://github.com/kubernetes/kubernetes/pull/64034), [@deads2k](https://github.com/deads2k))

#### Extensibility

- The community has been asking for continuing support of extensibility, so this cycle features more work around CRDs and API Machinery. Most of the enhancements in this cycle were from SIG API Machinery and related areas.

### Extensibility around core Kubernetes APIs

- `GetPodQOS(pod *core.Pod)` function now returns the stored value from `PodStatus.QOSClass`, if set. To compute/evaluate the value of `QOSClass` from scratch, `ComputePodQOS(pod*core.Pod)` must be used. ([#119665](https://github.com/kubernetes/kubernetes/pull/119665), [@vinaykul](https://github.com/vinaykul))

volume availability, the API now enables volume resizing and snapshotting. These features are in alpha.
The SIG also focused on providing more control over storage: the ability to set requests and
limits on ephemeral storage, the ability to specify mount options, more metrics, and improvements to Flex driver deployments.

[SIG Storage]: https://github.com/kubernetes/community/tree/master/sig-storage

## Before Upgrading

- Disable watchcache for events.k8.io/Event resource for compatibility with core/Event. ([#96117](https://github.com/kubernetes/kubernetes/pull/96117), [@wojtek-t](https://github.com/wojtek-t)) [SIG Scalability]

    - [**Cluster Federation**](#cluster-federation)
      - [Placement Policy](#placement-policy)
      - [Cluster Selection](#cluster-selection)
    - [**Instrumentation**](#instrumentation)
      - [Core Metrics API](#core-metrics-api)
    - [**Internationalization**](#internationalization)
    - [**kubectl (CLI)**](#kubectl-cli-1)
    - [**Networking**](#networking)
      - [Network Policy](#network-policy)

### SIG GCP

- GCE: decrease cpu requests on master node, to allow more components to fit on one core machine. ([#67504](https://github.com/kubernetes/kubernetes/pull/67504), [@loburm](https://github.com/loburm))