* explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {
    val lastFrame = outFrames.removeAt(outFrames.size - 1)
    require(length < bytesOut.size - lastFrame.start)

    // Move everything from bytesOut into a new buffer.
    val fullBuffer = Buffer()
    bytesOut.read(fullBuffer, bytesOut.size)

        when {
          it.sourceCodePoint1 < codePoint -> -1
          it.sourceCodePoint0 > codePoint -> 1
          else -> 0
        }
      }

    // Code points must be in 0..0x10ffff.
    require(index in mappings.indices) { "unexpected code point: $codePoint" }

    val mapping = mappings[index]
    var result = true

    when (mapping.type) {
      TYPE_IGNORED -> Unit

some connectivity failures. In this case, the `connectFailed()` event is not terminal and not followed by `callFailed()`. Event listeners will receive multiple events of the same type when retries are attempted.

A single HTTP call may require follow-up requests to be made to handle authentication challenges, redirects, and HTTP-layer timeouts. In such cases multiple connections, requests, and responses may be attempted. Follow-ups are another reason a single call may trigger multiple events...

  open fun getSelectedProtocol(sslSocket: SSLSocket): String? = null

  /** For MockWebServer. This returns the inbound SNI names. */
  @SuppressLint("NewApi")
  @IgnoreJRERequirement // This function is overridden to require API >= 24.
  open fun getHandshakeServerNames(sslSocket: SSLSocket): List<String> {
    val session = sslSocket.session as? ExtendedSSLSession ?: return listOf()

    upstreamSize: Long,
    metadataSize: Long,
  ) {
    val header =
      Buffer().apply {
        write(prefix)
        writeLong(upstreamSize)
        writeLong(metadataSize)
        require(size == FILE_HEADER_SIZE)
      }

    val fileOperator = FileOperator(file!!.channel)
    fileOperator.write(0, header, FILE_HEADER_SIZE)
  }

  @Throws(IOException::class)

  if (address[11] != 255.toByte()) return false

  return true
}

/** Encodes an IPv4 address in canonical form according to RFC 4001. */
internal fun inet4AddressToAscii(address: ByteArray): String {
  require(address.size == 4)
  return Buffer()
    .writeDecimalLong((address[0] and 0xff).toLong())
    .writeByte('.'.code)
    .writeDecimalLong((address[1] and 0xff).toLong())
    .writeByte('.'.code)

 *  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

    assertThat(parse("http://[0:0:0:0:0:0:0:0]/").host).isEqualTo("::")
    assertThat(parse("http://[::ffff:c0a8:1fe]/").host).isEqualTo("192.168.1.254")
  }

  /**
   * The builder permits square braces but does not require them.
   */
  @Test
  fun hostIpv6Builder() {
    val base = parse("http://example.com/")
    assertThat(base.newBuilder().host("[::1]").build().toString())
      .isEqualTo("http://[::1]/")

  }

private fun checkSupportResponse(
  name: String,
  response: Response?,
) {
  response?.apply {
    require(networkResponse == null) { "$name.networkResponse != null" }
    require(cacheResponse == null) { "$name.cacheResponse != null" }
    require(priorResponse == null) { "$name.priorResponse != null" }
  }
}

fun Response.Builder.commonPriorResponse(priorResponse: Response?) =
  apply {

      writeShort(0) // additional

      val nameBuf = Buffer()
      val labels = host.split('.').dropLastWhile { it.isEmpty() }
      for (label in labels) {
        val utf8ByteCount = label.utf8Size()
        require(utf8ByteCount == label.length.toLong()) { "non-ascii hostname: $host" }
        nameBuf.writeByte(utf8ByteCount.toInt())
        nameBuf.writeUtf8(label)
      }
      nameBuf.writeByte(0) // end