T[] castBuffer = (T[]) buffer;
    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

    }

    public PluginDescriptor build(ReaderSupplier readerSupplier, String source) throws PlexusConfigurationException {
        try (BufferedReader br = new BufferedReader(readerSupplier.open(), BUFFER_SIZE)) {
            br.mark(BUFFER_SIZE);
            XMLStreamReader xsr = XMLInputFactory.newFactory().createXMLStreamReader(br);
            xsr.nextTag();
            String nsUri = xsr.getNamespaceURI();