* doing HTTPS through an HTTP proxy, or HTTP/2 prior knowledge through an HTTP proxy.
     *
     * When a new connection is received, all in-tunnel responses are served before the connection is
     * upgraded to HTTPS or HTTP/2.
     */
    fun inTunnel() =
      apply {
        removeHeader("Content-Length")
        inTunnel = true
      }

  fun setBody(body: Buffer) =
    apply {
      setHeader("Content-Length", body.size)
      this.body = body.clone() // Defensive copy.
    }

  fun setBody(body: String): MockResponse = setBody(Buffer().writeUtf8(body))

  fun setChunkedBody(
    body: Buffer,
    maxChunkSize: Int,
  ) = apply {
    removeHeader("Content-Length")
    headersBuilder.add(CHUNKED_BODY_HEADER)