*  Fix: Don't lose HTTP/2 flow control bytes when incoming data races with a stream close. If this
    happened enough then eventually the connection would stall.

 *  Fix: Acknowledge and apply inbound HTTP/2 settings atomically. Previously we had a race where we
    could use new flow control capacity before acknowledging it, causing strict HTTP/2 servers to
    fail the call.

add headers with a fluent builder API.

```java
MockResponse response = new MockResponse()
    .addHeader("Content-Type", "application/json; charset=utf-8")
    .addHeader("Cache-Control", "no-cache")
    .setBody("{}");
```

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

```java
response.throttleBody(1024, 1, TimeUnit.SECONDS);

    val url = "http://host/#\u0080".toHttpUrl()
    assertThat(url.toString()).isEqualTo("http://host/#\u0080")
    assertThat(url.fragment).isEqualTo("\u0080")
    assertThat(url.encodedFragment).isEqualTo("\u0080")
    // Control characters may be stripped!
    assertThat(url.toUri()).isEqualTo(URI("http://host/#"))
  }

  @Test
  fun toUriWithControlCharacters() {
    // Percent-encoded in the path.

        .addHeader("icy-name:A2RRock")
        .addHeader("icy-pub:1")
        .addHeader("icy-url:http://www.A2Rradio.com")
        .addHeader("Server: Icecast 2.3.3-kh8")
        .addHeader("Cache-Control: no-cache")
        .addHeader("Pragma: no-cache")
        .addHeader("Expires: Mon, 26 Jul 1997 05:00:00 GMT")
        .addHeader("icy-metaint:16000")
        .body("mp3 data")
        .build(),
    )

    val headers = headersOf("Cache-Control", "max-age=12", "Pragma", "must-revalidate", "Pragma", "public")
    val cacheControl = parse(headers)
    assertThat(cacheControl.toString()).isEqualTo("max-age=12, public, must-revalidate")
  }

  @Test
  fun parseCacheControlHeaderValueIsRetained() {
    val value = "max-age=12"
    val headers = headersOf("Cache-Control", value)
    val cacheControl = parse(headers)

  /**
   * Notification that the receiving stream flow control window has changed.
   * [WindowCounter] generally carries the client view of total and acked bytes.
   */
  fun receivingStreamWindowChanged(
    streamId: Int,
    windowCounter: WindowCounter,
    bufferSize: Long,
  )

  /**
   * Notification that the receiving connection flow control window has changed.

            "0000a6d000603617069c012c0300005000100000cde000c04737461720463313072c012c04200010001000" +
            "0003b00049df00112",
        )
          .newBuilder()
          .setHeader("cache-control", "private, max-age=298")
          .build(),
      )
    }

    var result = cachedDns.lookup("google.com")
    assertThat(result).containsExactly(address("157.240.1.18"))

    when {
      name.equals("Cache-Control", ignoreCase = true) -> {
        if (headerValue != null) {
          // Multiple cache-control headers means we can't use the raw value.
          canUseHeaderValue = false
        } else {
          headerValue = value
        }
      }
      name.equals("Pragma", ignoreCase = true) -> {
        // Might specify additional cache-control params. We invalidate just in case.

timeout elapses. If we get bytes but there's nobody asking for them, we buffer them. We don't consider bytes as delivered for flow control until they're consumed by the application.

Consider an application streaming a video over http/2. Perhaps the user pauses the video and the application stops reading bytes from this stream. The buffer will fill up, and flow control prevents the server from sending more data on this stream. When the user unpauses her video the buffer drains, the read is acknowledged,...

  }

fun Request.Builder.commonCacheControl(cacheControl: CacheControl): Request.Builder {
  val value = cacheControl.toString()
  return when {
    value.isEmpty() -> removeHeader("Cache-Control")
    else -> header("Cache-Control", value)
  }
}

fun Request.Builder.commonGet(): Request.Builder = method("GET", null)

fun Request.Builder.commonHead(): Request.Builder = method("HEAD", null)