) {
    val increment: Long
    try {
      if (length != 4) throw IOException("TYPE_WINDOW_UPDATE length !=4: $length")
      increment = source.readInt() and 0x7fffffffL
      if (increment == 0L) throw IOException("windowSizeIncrement was 0")
    } catch (e: Exception) {
      logger.fine(frameLog(true, streamId, length, TYPE_WINDOW_UPDATE, flags))
      throw e
    }
    if (logger.isLoggable(FINE)) {
      logger.fine(

        length = 4,
        type = TYPE_WINDOW_UPDATE,
        flags = FLAG_NONE,
      )
      sink.writeInt(windowSizeIncrement.toInt())
      sink.flush()
    }
  }

  @Throws(IOException::class)
  fun frameHeader(
    streamId: Int,
    length: Int,
    type: Int,
    flags: Int,
  ) {
    if (type != TYPE_WINDOW_UPDATE && logger.isLoggable(FINE)) {

    }
  }

  @Test fun windowUpdateRoundTrip() {
    val expectedWindowSizeIncrement: Long = 0x7fffffff
    writeMedium(frame, 4) // length
    frame.writeByte(Http2.TYPE_WINDOW_UPDATE)
    frame.writeByte(FLAG_NONE)
    frame.writeInt(expectedStreamId)
    frame.writeInt(expectedWindowSizeIncrement.toInt())

    // Check writer sends the same bytes.