implementation must:
</p>

<ul>
	<li>Represent integer constants with at least 256 bits.</li>

	<li>Represent floating-point constants, including the parts of
	    a complex constant, with a mantissa of at least 256 bits
	    and a signed binary exponent of at least 16 bits.</li>

	<li>Give an error if unable to represent an integer constant
	    precisely.</li>

- Scheduler alpha metrics binding_duration_seconds and scheduling_algorithm_preemption_evaluation_seconds are deprecated, Both of those metrics are now covered as part of framework_extension_point_duration_seconds, the former as a PostFilter the latter and a Bind plugin. The plan is to remove both in 1.21 ([#95001](https://github.com/kubernetes/kubernetes/pull/95001), [@arghya88](https://github.com/arghya88)) [SIG Instrumentation and Scheduling]

  - **apiserver_flowcontrol_priority_level_seat_count_watermarks**: histograms of high and low watermarks of number of seats occupied by executing requests (both regular and final-delay phases included), broken down by priority_level.

- [IPv4/IPv6 dual-stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack) enables the allocation of both IPv4 and IPv6 addresses to Pods and Services.
- [API Server Network Proxy](https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/1281-network-proxy/README.md) going alpha in 1.16.

### Extensibility around core Kubernetes APIs

#### CustomResourceDefinitions Pruning

* Fix kube-apiserver crash when patching TPR data ([#44612](https://github.com/kubernetes/kubernetes/pull/44612), [@nikhita](https://github.com/nikhita))

- github.com/armon/go-radix: [7fddfc3](https://github.com/armon/go-radix/tree/7fddfc3)
- github.com/bgentry/speakeasy: [v0.1.0](https://github.com/bgentry/speakeasy/tree/v0.1.0)
- github.com/bits-and-blooms/bitset: [v1.2.0](https://github.com/bits-and-blooms/bitset/tree/v1.2.0)
- github.com/bketelsen/crypt: [v0.0.4](https://github.com/bketelsen/crypt/tree/v0.0.4)

- Structured logging of NamespacedName was inconsistent with klog.KObj. Now both use lower case field names and namespace is optional. ([#117238](https://github.com/kubernetes/kubernetes/pull/117238), [@pohly](https://github.com/pohly)) [SIG API Machinery, Architecture and Instrumentation]

## Dependencies

## Urgent Upgrade Notes
### (No, really, you MUST read this before you upgrade)
#### Cluster Lifecycle

    * The body size limit does not apply to subresources like pods/proxy that proxy request content to another server.