override fun writeTo(sink: BufferedSink) {
        sink.writeUtf8("<element/>")
        sink.flush()
      }
    }

    server.enqueue(MockResponse(code = 201))
    server.enqueue(MockResponse(code = 204))
    server.enqueue(MockResponse(code = 204))

    val endpointUrl = server.url("/endpoint")

    var request =
      Request
        .Builder()
        .url(endpointUrl)

### Kotlin
```kotlin
val response = MockResponse.Builder()
  .addHeader("Content-Type", "application/json; charset=utf-8")
  .addHeader("Cache-Control", "no-cache")
  .body("{}")
  .build()
```

MockResponse can be used to simulate a slow network. This is useful for
testing timeouts and interactive testing.

### Java
```java
MockResponse response = new MockResponse.Builder()

    // Set up a same-connection retry.
    serverIpv4.enqueue(
      MockResponse
        .Builder()
        .onRequestStart(CloseStream(ErrorCode.REFUSED_STREAM.httpCode))
        .build(),
    )
    serverIpv4.enqueue(
      MockResponse(body = "this was the 2nd request on IPv4"),
    )
    serverIpv6.enqueue(
      MockResponse(body = "unexpected call to IPv6"),
    )

    val mockResponse =
      MockResponse
        .Builder()
        .doNotReadRequestBody()
        .trailers(headersOf("caboose", "xyz"))

    // Trailers always work for HTTP/2, but only for chunked bodies in HTTP/1.
    if (http2) {
      mockResponse.body("abc")
    } else {
      mockResponse.chunkedBody("abc", 1)
    }

  }

  @Test
  fun secondCallEventSequence() {
    enableTlsWithTunnel()
    server.protocols = Arrays.asList(Protocol.HTTP_2, Protocol.HTTP_1_1)
    server.enqueue(MockResponse())
    server.enqueue(MockResponse())
    client
      .newCallWithListener(
        Request
          .Builder()
          .url(server.url("/"))
          .build(),
      ).execute()
      .close()

        .requestIOException()
        .exhaustResponse()
    server.enqueue(
      MockResponse
        .Builder()
        .clearHeaders()
        .code(HttpURLConnection.HTTP_MOVED_PERM)
        .addHeader("Location: /b")
        .socketHandler(body)
        .build(),
    )
    server.enqueue(
      MockResponse
        .Builder()
        .body("this is /b")
        .build(),
    )
    val call =

  }

  @Test
  fun receiveAndSendMultipleCookies() {
    server.enqueue(
      MockResponse
        .Builder()
        .addHeader("Set-Cookie", "a=android")
        .addHeader("Set-Cookie", "b=banana")
        .build(),
    )
    server.enqueue(MockResponse())
    val cookieManager = CookieManager(null, CookiePolicy.ACCEPT_ORIGINAL_SERVER)
    client =
      client

  @Test
  fun disconnectAtStart() {
    server.enqueue(
      MockResponse
        .Builder()
        .onRequestStart(CloseSocket())
        .build(),
    )
    server.enqueue(MockResponse()) // The jdk's HttpUrlConnection is a bastard.
    server.enqueue(MockResponse())
    try {
      server
        .url("/a")
        .toUrl()
        .openConnection()

  @Disabled("Not actually failing where expected")
  @Test
  fun disconnectAtStart() {
    server.enqueue(
      MockResponse()
        .setSocketPolicy(SocketPolicy.DISCONNECT_AT_START),
    )
    server.enqueue(MockResponse()) // The jdk's HttpUrlConnection is a bastard.
    server.enqueue(MockResponse())
    try {
      server
        .url("/a")
        .toUrl()
        .openConnection()

        WitnessRegisterResponse mockResponse = mock(WitnessRegisterResponse.class);
        lenient().when(mockResponse.isSuccess()).thenReturn(true);
        lenient().when(mockResponse.getRegistrationId()).thenReturn("test-reg-123");

        WitnessRpcClient mockRpc = mock(WitnessRpcClient.class);
        lenient().when(mockRpc.register(any(WitnessRegisterRequest.class))).thenReturn(mockResponse);