/** Initialized in [callStart]. */
  private var callStackTrace: Any? = null

  /** Finds an exchange to send the next request and receive the next response. */
  private var exchangeFinder: ExchangeFinder? = null

  var connection: RealConnection? = null
    private set
  private var timeoutEarlyExit = false

  /**

        synchronized(this@Relay) {
          upstreamReader = null
          ******@****.***All()
        }
      }
    }

    override fun timeout(): Timeout = timeout

    @Throws(IOException::class)
    override fun close() {
      if (fileOperator == null) return // Already closed.
      fileOperator = null

      var fileToClose: RandomAccessFile? = null
      synchronized(this@Relay) {
        sourceCount--

       * file that gets bundled with the application.
       */
      private fun trustedCertificatesInputStream(): InputStream {
        ... // Full source omitted. See sample.
      }

      private fun trustManagerForCertificates(inputStream: InputStream): X509TrustManager {
        ... // Full source omitted. See sample.
      }
    ```
=== ":material-language-java: Java"
    ```java
      private final OkHttpClient client;

       <version>1.4.0</version>
     </dependency>
     ```

 *  **`Request.Builder` no longer accepts null if a request body is required.**
    Passing null will now fail for request methods that require a body. Instead
    use an empty body such as this one:

    ```java
        RequestBody.create(null, new byte[0]);
    ```

 * **`CertificatePinner` now supports wildcard hostnames.** As always with

  if (result.containsInvalidLabelLengths()) return null

  return result
}

internal fun idnToAscii(host: String): String? {
  val bufferA = Buffer().writeUtf8(host)
  val bufferB = Buffer()

  // 1. Map, from bufferA to bufferB.
  while (!bufferA.exhausted()) {
    val codePoint = bufferA.readUtf8CodePoint()
    if (!IDNA_MAPPING_TABLE.map(codePoint, bufferB)) return null
  }

      var sha1: ByteString? = null
      var sha256: ByteString? = null

      for (pin in pins) {
        when (pin.hashAlgorithm) {
          "sha256" -> {
            if (sha256 == null) sha256 = peerCertificate.sha256Hash()
            if (pin.hash == sha256) return // Success!
          }
          "sha1" -> {
            if (sha1 == null) sha1 = peerCertificate.sha1Hash()

  open class Builder {
    internal var request: Request? = null
    internal var protocol: Protocol? = null
    internal var code = -1
    internal var message: String? = null
    internal var handshake: Handshake? = null
    internal var headers: Headers.Builder
    internal var body: ResponseBody = commonEmptyResponse
    internal var networkResponse: Response? = null
    internal var cacheResponse: Response? = null

        if (openJSSE != null) {
          return openJSSE
        }
      }

      // An Oracle JDK 9 like OpenJDK, or JDK 8 251+.
      val jdk9 = Jdk9Platform.buildIfSupported()

      if (jdk9 != null) {
        return jdk9
      }

      // An Oracle JDK 8 like OpenJDK, pre 251.
      val jdkWithJettyBoot = Jdk8WithJettyBootPlatform.buildIfSupported()

      if (jdkWithJettyBoot != null) {

    assertThat(body.string()).isEqualTo(text)
  }

  companion object {
    @JvmOverloads
    fun body(
      hex: String,
      charset: String? = null,
    ): ResponseBody {
      val mediaType = if (charset == null) null else "any/thing; charset=$charset".toMediaType()
      return hex.decodeHex().toResponseBody(mediaType)
    }

    fun exhaust(reader: Reader): String {

        RealConnection(
          taskRunner = taskRunner,
          connectionPool = connectionPool,
          route = route,
          rawSocket = null,
          socket = socket,
          handshake = null,
          protocol = null,
          source = null,
          sink = null,
          pingIntervalMillis = 0,
          ConnectionListener.NONE,
        )
      result.idleAtNs = idleAtNs
      return result
    }