ASCII text.  There are four ways to represent the integer value
as a numeric constant: <code>\x</code> followed by exactly two hexadecimal
digits; <code>\u</code> followed by exactly four hexadecimal digits;
<code>\U</code> followed by exactly eight hexadecimal digits, and a
plain backslash <code>\</code> followed by exactly three octal digits.
In each case the value of the literal is the value represented by

    * `kubectl create configmap` has a new option `--from-env-file` that populates a configmap from file which follows a key=val format for each line. ([#38882](https://github.com/kubernetes/kubernetes/pull/38882), [@fraenkel](https://github.com/fraenkel))

    * `kubectl create secret` has a new option `--from-env-file` that populates a secret from file which follows a key=val format for each line.

  * Printing/describe

- Implemented API streaming for the `watch-cache`
  
  When `sendInitialEvents` `ListOption` is set together with `watch=true`, it begins the watch stream with synthetic init events followed by a synthetic "Bookmark" after which the server continues streaming events. ([#110960](https://github.com/kubernetes/kubernetes/pull/110960), [@p0lyn0mial](https://github.com/p0lyn0mial))
- Introduced API for streaming.
  

- Implemented API for streaming for the `etcd` store implementation.
  When `sendInitialEvents ListOption` is set together with `watch=true`, it begins the watch stream with synthetic init events followed by a synthetic `Bookmark`, after which the server continues streaming events. ([#119557](https://github.com/kubernetes/kubernetes/pull/119557), [@p0lyn0mial](https://github.com/p0lyn0mial))

  optional string protocol = 3;

  // The application protocol for this port.
  // This is used as a hint for implementations to offer richer behavior for protocols that they understand.
  // This field follows standard Kubernetes label syntax.
  // Valid values are either:
  //
  // * Un-prefixed protocol names - reserved for IANA standard service names (as per
  // RFC-6335 and https://www.iana.org/assignments/service-names).

- The plugin mechanism functionality now closely follows the git plugin design ([#66876](https://github.com/kubernetes/kubernetes/pull/66876), [@juanvallejo](https://github.com/juanvallejo))

- YAML documents separators ("---") can now be followed by whitespace and comments ("# ....") on the same line. This fixes a bug where documents starting with a comment after the separator were ignored. Other types of content on the same line will result in an error. ([#103457](https://github.com/kub...

- Modify DNS-1123 error messages to indicate that RFC 1123 is not followed exactly ([#94182](https://github.com/kubernetes/kubernetes/pull/94182), [@mattfenwick](https://github.com/mattfenwick)) [SIG API Machinery, Apps, Auth, Network and Node]

- Kube-apiserver: redirects from backend API servers are no longer followed when checking availability with requests to `/apis/$group/$version` ([#112772](https://github.com/kubernetes/kubernetes/pull/112772), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Testing]

- The kube-apiserver's Prometheus metrics have been extended with some that describe the costs of handling LIST requests.  They are as follows.
  - *apiserver_cache_list_total*: Counter of LIST requests served from watch cache, broken down by resource_prefix and index_name