- Added `--output plaintext-openapiv2` argument to kubectl explain to use old openapiv2 `explain` implementation. ([#115480](https://github.com/kubernetes/kubernetes/pull/115480), [@alexzielenski](https://github.com/alexzielenski))

* Kubectl explain now prints out the Kind and API version of the resource being explained. ([#55689](https://github.com/kubernetes/kubernetes/pull/55689), [@luksa](https://github.com/luksa))

### Cluster Lifecycle

- Fixed bug where explain was not properly respecting jsonpaths. ([#115694](https://github.com/kubernetes/kubernetes/pull/115694), [@mpuckett159](https://github.com/mpuckett159))

- Fixed `kubectl explain` to show enum for field types if they were defined. ([#123023](https://github.com/kubernetes/kubernetes/pull/123023), [@ah8ad3](https://github.com/ah8ad3))

*   `kubectl explain` now explains `apiservices` and `customresourcedefinition`. (Updated to use OpenAPI instead of Swagger 1.2.) ([#53228](https://github.com/kubernetes/kubernetes/pull/53228),[ @apelisse](https://github.com/apelisse))

#### CustomResourceDefinition OpenAPI Publishing

OpenAPI specs for native types have long been served at /openapi/v2, and they are consumed by a number of components, notably kubectl client-side validation, kubectl explain and OpenAPI based client generators.

With Kubernetes 1.15 as beta, OpenAPI schemas are also published for CRDs, as long as their schemas are structural.

The precise details are relevant for Go implementations,
affect the specifics of error messages (such as whether
a compiler reports a type inference or other error),
and may explain why type inference fails in unusual code situations.
But by and large these rules can be ignored when writing Go code:
type inference is designed to mostly "work as expected",

    /** The key of the configuration. e.g. true */
    String RESPONSE_HIGHLIGHT_content_title_ENABLED = "response.highlight.content_title.enabled";

    /** The key of the configuration. e.g. application/pdf,text/plain */
    String RESPONSE_INLINE_MIMETYPES = "response.inline.mimetypes";

    /** The key of the configuration. e.g. fess.search */
    String INDEX_DOCUMENT_SEARCH_INDEX = "index.document.search.index";

  "Local" routes traffic to node-local endpoints only, and traffic is dropped if no node-local endpoints are ready.
  The default value is "Cluster". ([#96600](https://github.com/kubernetes/kubernetes/pull/96600), [@maplain](https://github.com/maplain)) [SIG API Machinery, Apps and Network]

- `kubeadm`: updated warning message when swap space is detected. When swap is
  active on Linux, `kubeadm` explains that swap is supported for cgroup v2 only and
  is beta but disabled by default. ([#120198](https://github.com/kubernetes/kubernetes/pull/120198), [@pacoxu](https://github.com/pacoxu))