*  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.

    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"))

  }

  companion object {
    /**
     * Cache control request directives that require network validation of responses. Note that such
     * requests may be assisted by the cache via conditional GET requests.
     */
    @JvmField
    val FORCE_NETWORK = commonForceNetwork()

    /**
     * Cache control request directives that uses the cache only, even if the cached response is

    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.

    open fun headers(headers: Headers) = commonHeaders(headers)

    /**
     * Sets this request's `Cache-Control` header, replacing any cache control headers already
     * present. If [cacheControl] doesn't define any directives, this clears this request's
     * cache-control headers.
     */
    open fun cacheControl(cacheControl: CacheControl): Builder = commonCacheControl(cacheControl)

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,...