shares connections when hosts share both IP addresses and certificates, such as `squareup.com`
    and `www.squareup.com`. If a server refuses such sharing it will return HTTP 421 and OkHttp will
    automatically retry on an unshared connection.
 *  Fix: Don't crash if a TLS tunnel's response body is truncated.
 *  Fix: Don't track unusable routes beyond their usefulness. We had a bug where we could track

   */
  class AddressPolicy(
    /**
     * How many concurrent calls should be possible to make at any time.
     * The pool will routinely try to pre-emptively open connections to satisfy this minimum.
     * Connections will still be closed if they idle beyond the keep-alive but will be replaced.
     */
    @JvmField val minimumConcurrentCalls: Int = 0,

   * [requestBodyOpen], [responseBodyOpen], and [expectMoreExchanges].
   *
   * This will release the connection if it is still held.
   *
   * It will also notify the listener that the call completed; either successfully or
   * unsuccessfully.
   *
   * If the call was canceled or timed out, this will wrap [e] in an exception that provides that
   * additional context. Otherwise [e] is returned as-is.
   */

   * in practice. To simplify the implementation, we've avoided implementing the flexible rules in
   * favor of supporting what's actually used in practice. That means if these assertions ever fail,
   * the implementation will need to be revisited to support a more flexible rule.
   */
  private fun assertWildcardRule(rule: String) {
    check(rule.startsWith(WILDCARD_CHAR)) {
      """Wildcard Assertion Failure: '$rule'

  fun sendFrame(): Http2Writer {
    outFrames.add(OutFrame(frameCount++, bytesOut.size, false))
    return writer
  }

  /**
   * Shortens the last frame from its original length to `length`. This will cause the peer to
   * close the socket as soon as this frame has been written; otherwise the peer stays open until
   * explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {

  private const val INITIAL_BIAS = 72
  private const val INITIAL_N = 0x80

  /**
   * Returns null if any label is oversized so much that the encoder cannot encode it without
   * integer overflow. This will not return null for labels that fit within the DNS size
   * limits.
   */
  fun encode(string: String): String? {
    var pos = 0
    val limit = string.length
    val result = Buffer()

    while (pos < limit) {

        connectionPool.scheduleCloser()
      }
    }
  }

  override fun handshake(): Handshake? = handshake

  /** Track a bad route in the route database. Other routes will be attempted first. */
  internal fun connectFailed(
    client: OkHttpClient,
    failedRoute: Route,
    failure: IOException,
  ) {
    // Tell the proxy selector when we fail to connect on a fresh connection.

      Thread.currentThread().interrupt() // Retain interrupted status.
      throw InterruptedIOException()
    }
  }

  /**
   * The Okio timeout watchdog will call [timedOut] if the timeout is reached. In that case we close
   * the stream (asynchronously) which will notify the waiting thread.
   */
  internal inner class StreamTimeout : AsyncTimeout() {
    override fun timedOut() {
      closeLater(ErrorCode.CANCEL)

   * was acquired, or null if no connection was acquired. The acquired connection will also be
   * given to [connectionUser] who may (for example) assign it to a [RealCall.connection].
   *
   * This confirms the returned connection is healthy before returning it. If this encounters any
   * unhealthy connections in its search, this will clean them up.
   *

   * client presents a certificate that is [trusted][TrustManager] the handshake will
   * proceed normally. The connection will also proceed normally if the client presents no
   * certificate at all! But if the client presents an untrusted certificate the handshake
   * will fail and no connection will be established.
   */
  fun requestClientAuth() {
    this.clientAuth = CLIENT_AUTH_REQUESTED
  }