@Throws(IOException::class)
  fun start() {
    idleAtNs = System.nanoTime()
    if (protocol == Protocol.HTTP_2 || protocol == Protocol.H2_PRIOR_KNOWLEDGE) {
      startHttp2()
    }
  }

  @Throws(IOException::class)
  private fun startHttp2() {
    javaNetSocket.soTimeout = 0 // HTTP/2 connection timeouts are set per-stream.
    val flowControlListener = connectionListener as? FlowControlListener ?: FlowControlListener.None