/**
     * Returns the subset of the headers in [requestHeaders] that impact the content of the
     * response's body.
     */
    private fun varyHeaders(
      requestHeaders: Headers,
      responseHeaders: Headers,
    ): Headers {
      val varyFields = responseHeaders.varyFields()
      if (varyFields.isEmpty()) return Headers.EMPTY

      val result = Headers.Builder()

    val authority = request.headers["Host"] // Has host and port.
    val fancyRequest =
      Request
        .Builder()
        .url("$scheme://$authority/")
        .headers(request.headers)
        .build()
    val fancyResponse =
      Response
        .Builder()
        .code(webSocketResponse.code)
        .message(webSocketResponse.message)
        .headers(webSocketResponse.headers)

    val body = "hello".toRequestBody()
    val headers = headersOf("User-Agent", "RequestTest")
    val method = "PUT"
    val request =
      Request(
        url = url,
        headers = headers,
        method = method,
        body = body,
      )
    assertThat(request.url).isEqualTo(url)
    assertThat(request.headers).isEqualTo(headers)
    assertThat(request.method).isEqualTo(method)

/// warning

Before setting `convert_underscores` to `False`, bear in mind that some HTTP proxies and servers disallow the usage of headers with underscores.

///

## Duplicate headers { #duplicate-headers }

It is possible to receive duplicate headers. That means, the same header with multiple values.

You can define those cases using a list in the type declaration.

    method = "GET",
    target = "/",
    version = "HTTP/2",
  )

private fun requestUrl(
  socket: MockWebServerSocket,
  requestLine: RequestLine,
  headers: Headers,
): HttpUrl {
  val hostAndPort =
    headers[":authority"]
      ?: headers["Host"]
      ?: when (val inetAddress = socket.localAddress) {
        is Inet6Address -> "[${inetAddress.hostAddress}]:${socket.localPort}"

  }

  @Test
  fun headers() {
    var headers: Headers = headersOf("", "")
    headers = mapOf("" to "").toHeaders()
    val get: String? = headers[""]
    val date: Date? = headers.getDate("")
    val instant: Instant? = headers.getInstant("")
    val size: Int = headers.size
    val name: String = headers.name(0)
    val value: String = headers.value(0)
    val names: Set<String> = headers.names()

            - init_headers
            - headers
            - set_cookie
            - delete_cookie

::: fastapi.responses.HTMLResponse
    options:
        members:
            - charset
            - status_code
            - media_type
            - body
            - background
            - raw_headers
            - render
            - init_headers
            - headers
            - set_cookie

  fun writeRequest(
    headers: Headers,
    requestLine: String,
  ) {
    check(state == STATE_IDLE) { "state: $state" }
    socket.sink.writeUtf8(requestLine).writeUtf8("\r\n")
    for (i in 0 until headers.size) {
      socket.sink
        .writeUtf8(headers.name(i))
        .writeUtf8(": ")
        .writeUtf8(headers.value(i))
        .writeUtf8("\r\n")
    }

        return contentException;
    }

    /**
     * Sets the headers for the response.
     *
     * @param headers the headers to set.
     */
    public void setHeaders(final Map<String, List<String>> headers) {
        if (headers != null) {
            final Map<String, List<String>> map = new HashMap<>();
            headers.entrySet().stream().filter(e -> e.getKey() != null)

    var headers: Headers = mockResponse.headers
    var trailers: Headers = mockResponse.trailers
    mockResponse = mockResponse.clearHeaders()
    mockResponse = mockResponse.addHeader("")
    mockResponse = mockResponse.addHeader("", "")
    mockResponse = mockResponse.addHeaderLenient("", Any())
    mockResponse = mockResponse.setHeader("", Any())
    mockResponse.headers = headersOf()