val result = if (flags < FLAGS.size) FLAGS[flags]!! else BINARY[flags]
    // Special case types that have overlap flag values.
    return when {
      type == TYPE_PUSH_PROMISE && flags and FLAG_END_PUSH_PROMISE != 0 -> {
        result.replace("HEADERS", "PUSH_PROMISE") // TODO: Avoid allocation.
      }
      type == TYPE_DATA && flags and FLAG_COMPRESSED != 0 -> {
        result.replace("PRIORITY", "COMPRESSED") // TODO: Avoid allocation.

    assertThat(frameLog(true, 3, 10000, TYPE_CONTINUATION, 0x4))
      .isEqualTo("<< 0x00000003 10000 CONTINUATION  END_HEADERS")
    assertThat(frameLog(true, 4, 10000, TYPE_PUSH_PROMISE, 0x4))
      .isEqualTo("<< 0x00000004 10000 PUSH_PROMISE  END_PUSH_PROMISE")
  }

  @Test
  fun flagOverlapOn0x20() {
    assertThat(frameLog(true, 3, 10000, TYPE_HEADERS, 0x20))
      .isEqualTo("<< 0x00000003 10000 HEADERS       PRIORITY")

    val request =
      Request.Builder()
        .url(url)
        .build()

    val promise = CompletableFuture<Response>()

    val call = client.newCall(request)
    call.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          promise.completeExceptionally(e)
        }

        override fun onResponse(

      flags = FLAG_ACK,
    )
    sink.flush()
  }

  /**
   * HTTP/2 only. Send a push promise header block.
   *
   * A push promise contains all the headers that pertain to a server-initiated request, and a
   * `promisedStreamId` to which response frames will be delivered. Push promise frames are sent as
   * a part of the response to `streamId`. The `promisedStreamId` has a priority of one greater than

  }

  @JsFunction
  interface IThenOnRejectedCallbackFn<V extends @Nullable Object> {
    V onInvoke(Object p0);
  }
}

/** Subset of the elemental2 Promise API. */
@JsType(isNative = true, namespace = JsPackage.GLOBAL, name = "Promise")
class Promise<T extends @Nullable Object> implements IThenable<T> {

  @JsFunction
  interface PromiseExecutorCallbackFn<T extends @Nullable Object> {
    @JsFunction

      weight: Int,
      exclusive: Boolean,
    )

    /**
     * HTTP/2 only. Receive a push promise header block.
     *
     * A push promise contains all the headers that pertain to a server-initiated request, and a
     * `promisedStreamId` to which response frames will be delivered. Push promise frames are sent
     * as a part of the response to `streamId`.
     *

    headersDelayAmount = delay
    headersDelayUnit = unit
  }

  fun getHeadersDelay(unit: TimeUnit): Long = unit.convert(headersDelayAmount, headersDelayUnit)

  fun withPush(promise: PushPromise) =
    apply {
      promises.add(promise)
    }

  fun withSettings(settings: Settings) =
    apply {
      this.settings = settings
    }

  fun withWebSocketUpgrade(listener: WebSocketListener) =

        Header(Header.TARGET_PATH, "/"),
      )

    // Write the push promise frame, specifying the associated stream ID.
    val headerBytes = literalHeaders(pushPromise)
    writeMedium(frame, (headerBytes.size + 4).toInt())
    frame.writeByte(Http2.TYPE_PUSH_PROMISE)
    frame.writeByte(Http2.FLAG_END_PUSH_PROMISE)
    frame.writeInt(expectedStreamId and 0x7fffffff)

    }

    override fun pushPromise(
      streamId: Int,
      associatedStreamId: Int,
      headerBlock: List<Header>,
    ) {
      this.type = Http2.TYPE_PUSH_PROMISE
      this.streamId = streamId
      this.associatedStreamId = associatedStreamId
      this.headerBlock = headerBlock
    }

    override fun alternateService(
      streamId: Int,
      origin: String,

       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
       * worth noting that we promise not to put nulls into the array in the first `size` elements.
       * We uphold that promise here because our callers promise that `elements` will not contain
       * nulls in its first `n` elements.
       */
      System.arraycopy(elements, 0, contents, size, n);
      size += n;