pings, but it did not track whether the reply pongs were received. With this
    update OkHttp requires that every ping receive a response: if it does not
    the connection will be closed and the listener's `onFailure()` method will
    be called.

    Web sockets have always been had pings, but pings on HTTP/2 connections is
    new in this release. Pings are used for connections that are busy carrying

 *
 *  * https://example.net/
 *
 *  * https://example.com/
 *
 * This is because those two hosts share the same IP address. This is an old, bad design decision
 * that makes `java.net.URL` unusable for many things. It shouldn't be used as a [Map] key or in a
 * [Set]. Doing so is both inefficient because equality may require a DNS lookup, and incorrect
 * because unequal URLs may be equal because of how they are hosted.
 *

     *
     * The default value of 0 disables client-initiated pings.
     */
    fun pingInterval(
      interval: Long,
      unit: TimeUnit,
    ) = apply {
      pingInterval = checkDuration("interval", interval, unit)
    }

    /**
     * Sets the interval between HTTP/2 and web socket pings initiated by this client. Use this to

        .pingInterval(Duration.ofMillis(500))
        .build()

    // Set up the server to ignore the socket. It won't respond to pings!
    server.enqueue(MockResponse.Builder().onRequestStart(Stall).build())

    // Make a call. It'll fail as soon as our pings detect a problem.
    val call = client.newCall(Request(server.url("/")))
    val executeAtNanos = System.nanoTime()

* Cross-build hyperkube and debian-iptables for ARM. Also add a flannel image ([#21617](https://github.com/kubernetes/kubernetes/pull/21617), [@luxas](https://github.com/luxas))
* Add a timeout to the sshDialer to prevent indefinite hangs. ([#23843](https://github.com/kubernetes/kubernetes/pull/23843), [@cjcullen](https://github.com/cjcullen))