* upgraded to HTTPS or HTTP/2.
     */
    fun inTunnel() =
      apply {
        removeHeader("Content-Length")
        inTunnel = true
      }

    /**
     * Adds an HTTP 1xx response to precede this response. Note that this response's
     * [headers delay][headersDelay] applies after this response is transmitted. Set a
     * headers delay on that response to delay its transmission.
     */