- kubectl: Added alpha support for customizing kubectl behavior using preferences from a `kuberc` file, separate from `kubeconfig`. ([#125230](https://github.com/kubernetes/kubernetes/pull/125230), [@ardaguclu](https://github.com/ardaguclu)) [SIG API Machinery, CLI and Testing]

none;\n  background-color: $breadcrumb-bg;\n  @include border-radius($breadcrumb-border-radius);\n}\n\n.breadcrumb-item {\n  // The separator between breadcrumbs (by default, a forward-slash: \"/\")\n  + .breadcrumb-item {\n    padding-left: $breadcrumb-item-padding;\n\n    &::before {\n      float: left; // Suppress inline spacings and underlining of the separator\n      padding-right: $breadcrumb-item-padding;\n      color: $breadcrumb-divider-color;\n      content: escape-svg($breadcrumb-divider);\n...

    and share it throughout the application. Requests that needs a customized
    client should call `OkHttpClient.newBuilder()` on that shared instance.
    This allows customization without the drawbacks of separate connection
    pools.

 *  **OkHttpClient is now stateless.** In the 2.x API `OkHttpClient` had getters
    and setters. Internally each request was forced to make its own complete

* kubelet's `--cni-bin-dir` option now accepts multiple comma-separated CNI binary directory paths, which are searched for CNI plugins in the given order. ([#58714](https://github.com/kubernetes/kubernetes/pull/58714), [@dcbw](https://github.com/dcbw))

  - `v1alpha1` has been removed.
  - `v1alpha3` has split apart `MasterConfiguration` into separate components; `InitConfiguration`, `ClusterConfiguration`, `JoinConfiguration`, `KubeletConfiguration`, and `KubeProxyConfiguration`
  - Different configuration types can be supplied all in the same file separated by `---`.
- Improved CRI handling
  - crictl is no longer required in docker-only setups.

* Action required: validation rule on metadata.initializers.pending[x].name is tightened. The initializer name needs to contain at least three segments separated by dots. If you create objects with pending initializers, (i.e., not relying on apiserver adding pending initializers according to initializerconfiguration), you need to update the initializer name in existing objects and in configuration files to...

- Kube-apiserver: multiple comma-separated protocols in a single X-Stream-Protocol-Version header are now recognized, in addition to multiple headers, complying with RFC2616 ([#89857](https://github.com/kubernetes/kubernetes/pull/89857), [@tedyu](https://github.com/tedyu)) [SIG API Machinery]...

  }

  // Inner Classes

  /**
   * Segments are specialized versions of hash tables. This subclass inherits from ReentrantLock
   * opportunistically, just to simplify some locking and avoid separate construction.
   */
  @SuppressWarnings("serial") // This class is never serialized.
  abstract static class Segment<
          K, V, E extends InternalEntry<K, V, E>, S extends Segment<K, V, E, S>>

    * ServiceDelimiter string Delimiter to use to separate overridden services (multiple services) Defaults to "&"
    * ServicenameDelimiter string Delimiter to use to separate servicename from its configuration parameters Defaults "|"
    * OverrideSeparator string Delimiter to use to separate region of occurrence, url and signing region for each override Defaults to ","

* Build hyperkube in hack/local-up-cluster instead of separate binaries ([#25627](https://github.com/kubernetes/kubernetes/pull/25627), [@luxas](https://github.com/luxas))