*  Fix: Retain binary-compatibility in `okhttp3.internal.HttpMethod`. Naughty third party SDKs
    import this and we want to ease upgrades for their users.


## Version 4.0.0-RC2

_2019-06-21_

 *  New: Require Kotlin 1.3.40.
 *  New: Change the Kotlin API from `File.toRequestBody()` to `File.asRequestBody()` and
    `BufferedSource.toResponseBody()` to `BufferedSource.asResponseBody()`. If the returned value

      apply {
        val maxAgeSeconds = maxAge.inWholeSeconds
        require(maxAgeSeconds >= 0) { "maxAge < 0: $maxAgeSeconds" }
        this.maxAgeSeconds = maxAgeSeconds.commonClampToInt()
      }

    fun maxStale(maxStale: Duration) =
      apply {
        val maxStaleSeconds = maxStale.inWholeSeconds
        require(maxStaleSeconds >= 0) { "maxStale < 0: $maxStaleSeconds" }

    flags: Int,
  ) {
    if (type != TYPE_WINDOW_UPDATE && logger.isLoggable(FINE)) {
      logger.fine(frameLog(false, streamId, length, type, flags))
    }
    require(length <= maxFrameSize) { "FRAME_SIZE_ERROR length > $maxFrameSize: $length" }
    require(streamId and 0x80000000.toInt() == 0) { "reserved bit set: $streamId" }
    sink.writeMedium(length)
    sink.writeByte(type and 0xff)
    sink.writeByte(flags and 0xff)

      // seconds are not supported by this syntax.
      require(year >= 1601)
      require(month != -1)
      require(dayOfMonth in 1..31)
      require(hour in 0..23)
      require(minute in 0..59)
      require(second in 0..59)

      GregorianCalendar(UTC).apply {
        isLenient = false
        set(Calendar.YEAR, year)

  ) : SerialTask {
    override fun start() {
      taskRunner.assertThreadHoldsLock()
      require(currentTask == this)
      activeThreads++

      tasksExecutor.execute {
        taskRunner.assertThreadDoesntHoldLock()
        require(currentTask == this)
        try {
          runnable.run()
          require(currentTask == this) { "unexpected current task: $currentTask" }
        } finally {

 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  private var receivedPongCount = 0

  /** True if we have sent a ping that is still awaiting a reply. */
  private var awaitingPong = false

  init {
    require("GET" == originalRequest.method) {
      "Request must be GET: ${originalRequest.method}"
    }

    this.key = ByteArray(16).apply { random.nextBytes(this) }.toByteString().base64()
  }

      require(Protocol.H2_PRIOR_KNOWLEDGE !in protocolList || protocolList.size == 1) {
        "protocols containing h2_prior_knowledge cannot use other protocols: $protocolList"
      }
      require(Protocol.HTTP_1_1 in protocolList || Protocol.H2_PRIOR_KNOWLEDGE in protocolList) {
        "protocols doesn't contain http/1.1: $protocolList"
      }