throwing in 5.0.0, we inadvertently removed the ability for callers to peek the trailers
    (by catching the `IllegalStateException` if they weren't available). This new API restores that
    capability.

 *  Fix: Don't crash on `trailers()` if the response doesn't have a body. We broke [Retrofit] users
    who read the trailers on the `raw()` OkHttp response, after its body was decoded.

* In-tree support for openstack credentials is now deprecated. please use the "client-keystone-auth" from the cloud-provider-openstack repository. details on how to use this new capability is documented [here](https://github.com/kubernetes/cloud-provider-openstack/blob/master/docs/using-client-keystone-auth.md) ([#64346](https://github.com/kubernetes/kubernetes/pull/64346), [@dims](https://github.com/dims))

     *
     * ```java
     * TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(
     * TrustManagerFactory.getDefaultAlgorithm());
     * trustManagerFactory.init((KeyStore) null);
     * TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();
     * if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager)) {

import java.net.SocketAddress
import java.net.SocketException
import java.net.SocketTimeoutException
import java.net.URI
import java.net.URLConnection
import java.net.UnknownHostException
import java.security.KeyStore
import java.security.cert.CertificateException
import java.security.cert.X509Certificate
import java.time.Duration
import java.util.Arrays
import java.util.EnumSet
import java.util.Locale

* Update busybox image link to gcr.io for kube-proxy. ([#53818](https://github.com/kubernetes/kubernetes/pull/53818), [@MrHohn](https://github.com/MrHohn))
* Restores the ability to apply network policy objects against the networking.k8s.io/v1 API ([#54106](https://github.com/kubernetes/kubernetes/pull/54106), [@liggitt](https://github.com/liggitt))

* kube-scheduler: restores ability to run without authentication configuration lookup permissions ([#71755](https://github.com/kubernetes/kubernetes/pull/71755), [@liggitt](https://github.com/liggitt))

* Restores --username and --password flags to kubectl ([#75451](https://github.com/kubernetes/kubernetes/pull/75451), [@liggitt](https://github.com/liggitt))

- Restores priority of static control plane pods in the cluster/gce/manifests control-plane manifests ([#89970](https://github.com/kubernetes/kubernetes/pull/89970), [@liggitt](https://github.com/liggitt)) [SIG Cluster Lifecycle and Node]

### Other notable changes

* Restores --username and --password flags to kubectl ([#75451](https://github.com/kubernetes/kubernetes/pull/75451), [@liggitt](https://github.com/liggitt))

* kube-scheduler: restores default leader election behavior. leader-elect command line parameter should "true" ([#60524](https://github.com/kubernetes/kubernetes/pull/60524), [@dims](https://github.com/dims))