#### kube-apiserver:
- in an `--encryption-provider-config` config file, an explicit `cacheSize: 0` parameter previously silently defaulted to caching 1000 keys. In Kubernetes 1.18, this now returns a config validation error. To disable caching, you can specify a negative cacheSize value in Kubernetes 1.18+.

   * specific length.
   *
   * <p>For example, if you need 1024-bit hash codes, you could join two {@link Hashing#sha512} hash
   * functions together: {@code Hashing.concatenating(Hashing.sha512(), Hashing.sha512())}.
   *
   * @since 19.0
   */
  public static HashFunction concatenating(
      HashFunction first, HashFunction second, HashFunction... rest) {

/**
 * Static methods for implementing hash-based collections.
 *
 * @author Kevin Bourrillion
 * @author Jesse Wilson
 * @author Austin Appleby
 */
@GwtCompatible
final class Hashing {
  private Hashing() {}

  /*
   * These should be ints, but we need to use longs to force GWT to do the multiplications with
   * enough precision.
   */
  private static final long C1 = 0xcc9e2d51;

   * specific length.
   *
   * <p>For example, if you need 1024-bit hash codes, you could join two {@link Hashing#sha512} hash
   * functions together: {@code Hashing.concatenating(Hashing.sha512(), Hashing.sha512())}.
   *
   * @since 19.0
   */
  public static HashFunction concatenating(
      HashFunction first, HashFunction second, HashFunction... rest) {

* Move private key parsing from serviceaccount/jwt.go to client-go/util/cert ([#40907](https://github.com/kubernetes/kubernetes/pull/40907), [@cblecker](https://github.com/cblecker))
* Caching added to the OIDC client auth plugin to fix races and reduce the time kubectl commands using this plugin take by several seconds. ([#38167](https://github.com/kubernetes/kubernetes/pull/38167), [@ericchiang](https://github.com/ericchiang))

* AWS: Remove duplicate calls to DescribeInstance during volume operations ([#39842](https://github.com/kubernetes/kubernetes/pull/39842), [@gnufied](https://github.com/gnufied))
* Caching added to the OIDC client auth plugin to fix races and reduce the time kubectl commands using this plugin take by several seconds. ([#38167](https://github.com/kubernetes/kubernetes/pull/38167), [@ericchiang](https://github.com/ericchiang))

   * closed.
   *
   * <p>Usage guidelines for this method:
   *
   * <ul>
   *   <li>Use this method only when calling an API that returns a {@link ListenableFuture} or a
   *       {@code ClosingFuture}. If possible, prefer calling {@link #catching(Class,
   *       ClosingFunction, Executor)} instead, with a function that returns the next value
   *       directly.

- Limit use of tags when calling EC2 API to prevent API throttling for very large clusters. ([#76749](https://github.com/kubernetes/kubernetes/pull/76749), [@mcrute](https://github.com/mcrute))

   * note that the execution order of all listeners is ultimately chosen by the implementations of
   * the supplied executors.
   *
   * <p>This method is idempotent. Calling it several times in parallel is semantically equivalent
   * to calling it exactly once.
   *
   * @since 10.0 (present in 1.0 as {@code run})
   */
  public void execute() {

 *   <li>an {@linkplain Thread#setUncaughtExceptionHandler uncaught exception handler}
 *   <li>a {@linkplain ThreadFactory#newThread backing thread factory}
 * </ul>
 *
 * <p>If no backing thread factory is provided, a default backing thread factory is used as if by
 * calling {@code setThreadFactory(}{@link Executors#defaultThreadFactory()}{@code )}.
 *