// what we did get (such as a 4xx response) without ever transmitting the request body.
        if ("100-continue".equals(request.header("Expect"), ignoreCase = true)) {
          exchange.flushRequest()
          responseBuilder = exchange.readResponseHeaders(expectContinue = true)
          exchange.responseHeadersStart()
          invokeStartEvent = false
        }
        if (responseBuilder == null) {

  @Throws(IOException::class)
  fun writeRequestHeaders(request: Request)

  /** Flush the request to the underlying socket. */
  @Throws(IOException::class)
  fun flushRequest()

  /** Flush the request to the underlying socket and signal no more bytes will be transmitted. */
  @Throws(IOException::class)
  fun finishRequest()

  /**

    }
    stream!!.readTimeout().timeout(chain.readTimeoutMillis.toLong(), TimeUnit.MILLISECONDS)
    stream!!.writeTimeout().timeout(chain.writeTimeoutMillis.toLong(), TimeUnit.MILLISECONDS)
  }

  override fun flushRequest() {
    http2Connection.flush()
  }

  override fun finishRequest() {
    stream!!.sink.close()
  }

  override fun readResponseHeaders(expectContinue: Boolean): Response.Builder? {