T[] castBuffer = (T[]) buffer;
    Arrays.sort(castBuffer, 0, bufferSize, comparator);
    if (bufferSize > k) {
      Arrays.fill(buffer, k, buffer.length, null);
      bufferSize = k;
      threshold = buffer[k - 1];
    }
    // Up to bufferSize, all elements of buffer are real Ts (not null unless T includes null)
    T[] topK = Arrays.copyOf(castBuffer, bufferSize);
    // we have to support null elements, so no ImmutableList for us

      }
      OPCODE_CONTROL_CLOSE -> {
        var code = CLOSE_NO_STATUS_CODE
        var reason = ""
        val bufferSize = controlFrameBuffer.size
        if (bufferSize == 1L) {
          throw ProtocolException("Malformed close payload length of 1.")
        } else if (bufferSize != 0L) {
          code = controlFrameBuffer.readShort().toInt()
          reason = controlFrameBuffer.readUtf8()