.add100Continue()
        .streamHandler(body)
        .build(),
    )
    val call =
      client.newCall(
        Request.Builder()
          .url(server.url("/"))
          .header("Expect", "100-continue")
          .post(AsyncRequestBody())
          .build(),
      )
    call.execute().use { response ->
      val requestBody = (call.request().body as AsyncRequestBody?)!!.takeSink()

 *        * headers ([responseHeadersStart], [responseHeadersEnd])
 *        * body ([responseBodyStart], [responseBodyEnd])
 *
 * This nesting is typical but not strict. For example, when calls use "Expect: continue" the
 * request body start and end events occur within the response header events. Similarly,
 * [duplex calls][RequestBody.isDuplex] interleave the request and response bodies.
 *

      val success = webSocket.send(message)
      if (!success) break
      messageCount++
      val queueSize = webSocket.queueSize()
      assertThat(queueSize).isBetween(0L, messageCount * message.size)
      // Expect to fail before enqueueing 32 MiB.
      assertThat(messageCount).isLessThan(32L)
    }

    // Confirm all sent messages were received, followed by a client-initiated close.
    val server = serverListener.assertOpen()

        .body("response")
        .build(),
    )
    val url = server.url("/").toUrl()
    val connection = url.openConnection() as HttpURLConnection
    connection.doOutput = true
    connection.setRequestProperty("Expect", "100-Continue")
    connection.outputStream.write("request".toByteArray(UTF_8))
    val inputStream = connection.inputStream
    val reader = BufferedReader(InputStreamReader(inputStream, UTF_8))

      Header("content-location", ""),
      Header("content-range", ""),
      Header("content-type", ""),
      Header("cookie", ""),
      Header("date", ""),
      Header("etag", ""),
      Header("expect", ""),
      Header("expires", ""),
      Header("from", ""),
      Header("host", ""),
      Header("if-match", ""),
      Header("if-modified-since", ""),
      Header("if-none-match", ""),

   * delimited by 'null'.
   *
   * @param callerIsIdle true if the caller isn't sending any more bytes until the peer responds.
   *     This is true after a `Expect-Continue` request, false for duplex requests, and false for
   *     all other requests.
   */
  @Throws(IOException::class)
  fun takeHeaders(callerIsIdle: Boolean = false): Headers {
    this.withLock {

requests and remove a common source of non-null assertions (`!!`) on the response body.

The alpha releases in the 5.0.0 series have production-quality code and an unstable API. We expect
to make changes to the APIs introduced in 5.0.0-alpha.X. These releases are safe for production use
and 'alpha' strictly signals that we're still experimenting with some new APIs. If you're eager for

  }

  private fun testRequestMethod(
    requestMethod: String,
    expectCached: Boolean,
    withOverride: Boolean = false,
  ) {
    // 1. Seed the cache (potentially).
    // 2. Expect a cache hit or miss.
    server.enqueue(
      MockResponse.Builder()
        .addHeader("Expires: " + formatDate(1, TimeUnit.HOURS))
        .addHeader("X-Response-ID: 1")
        .build(),
    )

          httpHeaders.add(name, value)
        } else {
          throw IllegalStateException()
        }
        if (name == "expect" && value.equals("100-continue", ignoreCase = true)) {
          // Don't read the body unless we've invited the client to send it.
          readBody = false
        }
      }

instead use the **(old) default value style**, if you call that function without FastAPI in **other place**, you have to **remember** to pass the arguments to the function for it to work correctly, otherwise the values will be different from what you expect (e.g. `QueryInfo` or something similar instead of `str`). And your editor won't complain, and Python won't complain running that function, only when the operations inside error out.

Because `Annotated` can have more than one metadata annotation,...