repeated APIResourceDiscovery resources = 2;

  // freshness marks whether a group version's discovery document is up to date.
  // "Current" indicates the discovery document was recently
  // refreshed. "Stale" indicates the discovery document could not
  // be retrieved and the returned discovery document may be
  // significantly out of date. Clients that require the latest
  // version of the discovery information be retrieved before

   *
   * This method returns false unless it is overridden by a subclass.
   *
   * By default OkHttp will attempt to retransmit request bodies when the original request fails
   * due to any of:
   *
   *  * A stale connection. The request was made on a reused connection and that reused connection
   *    has since been closed by the server.
   *  * A client timeout (HTTP 408).

  // TODO GET preferred order - with tests to confirm this
  // 1. successful fresh cached GET response
  // 2. unsuccessful (404, 500) fresh cached GET response
  // 3. successful network response
  // 4. successful stale cached GET response
  // 5. unsuccessful response
  @Test
  fun usesCache() {
    val cache = Cache(cacheFs, "cache".toPath(), (100 * 1024).toLong())

  private fun getCacheOnlyResponse(request: Request): Response? {
    if (client.cache != null) {
      try {
        // Use the cache without hitting the network first
        // 504 code indicates that the Cache is stale
        val onlyIfCached =
          CacheControl.Builder()
            .onlyIfCached()
            .build()

        var cacheUrl = request.url

        val cacheRequest =

        .header("Cache-Control", "max-stale=180")
        .build()
    val response = client.newCall(request).execute()
    assertThat(response.body.string()).isEqualTo("A")
    assertThat(response.header("Warning")).isEqualTo(
      "110 HttpURLConnection \"Response is stale\"",
    )
  }

  @Test
  fun requestMaxStaleDirectiveWithNoValue() {
    // Add a stale response to the cache.
    server.enqueue(

_2020-04-06_

**This release fixes a severe bug where OkHttp incorrectly detected and recovered from unhealthy
connections.** Stale or canceled connections were incorrectly attempted when they shouldn't have
been, leading to rare cases of infinite retries. Please upgrade to this release!

 *  Fix: don't return stale DNS entries in `DnsOverHttps`. We were caching DNS results indefinitely

  private var mostRecentRebuildFailed: Boolean = false

  /**
   * To differentiate between old and current snapshots, each entry is given a sequence number each
   * time an edit is committed. A snapshot is stale if its sequence number is not equal to its
   * entry's sequence number.
   */
  private var nextSequenceNumber: Long = 0

  private val cleanupQueue = taskRunner.newQueue()
  private val cleanupTask =

          },
        )
        .build()
    dns["san.com"] = Dns.SYSTEM.lookup(server.hostName).subList(0, 1)
    assert200Http2Response(execute(url), server.hostName)

    // Simulate a stale connection in the pool.
    connection.get()!!.socket().close()
    val sanUrl = url.newBuilder().host("san.com").build()
    assert200Http2Response(execute(sanUrl), "san.com")

 *  Fix: Handle 'Expect: 100 Continue' properly in MockWebServer.


## Version 3.8.1

_2017-06-18_

 *  Fix: Recover gracefully from stale coalesced connections. We had a bug where
    connection coalescing (introduced in OkHttp 3.7.0) and stale connection
    recovery could interact to cause a `NoSuchElementException` crash in the
    `RouteSelector`.


## Version 3.8.0

_2017-05-13_

 *  Fix: Avoid crashing when cache writing fails due to a full disk.
 *  Fix: Improve caching of private responses.
 *  Fix: Update cache-by-default response codes.
 *  Fix: Reused `Request.Builder` instances no longer hold stale URL fields.
 *  New: ConnectionSpec can now be configured to use the SSL socket's default
    cipher suites. To use, set the cipher suites to `null`.
 *  New: Support `DELETE` with a request body.