docs: public void serializeConfigurations(OutputStream os, List<AbstractCounterConfiguration> configs)
           throws XMLStreamException {
        BufferedOutputStream output = new BufferedOutputStream(os);
        XMLStreamWriter subWriter = XMLOutputFactory.newInstance().createXMLStreamWriter(output);
        XMLExtendedStreamWriter writer = new XMLExtendedStreamWriterImpl(subWriter);
        writer.writeStartDocument();
        writer.writeStartElement(Element.COUNTERS);
        writeConfigurations(writer, configs);
        writer.writeEndElement();
        writer.writeEndDocument();
        subWriter.close();
     }