@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() {
    val socket = this.socket!!
    val source = this.source!!
    val sink = this.sink!!
    socket.soTimeout = 0 // HTTP/2 connection timeouts are set per-stream.