private void addHeaders(List<? extends Column> columns, XHTMLContentHandler xhtml)
            throws SAXException {
        xhtml.startElement("thead");
        xhtml.startElement("tr");
        for (Column c : columns) {
            xhtml.startElement("th");
            xhtml.characters(c.getName());
            xhtml.endElement("th");
        }
        xhtml.endElement("tr");
        xhtml.endElement("thead");

    }
Internal class.  Needs to be instantiated for each parse because of
the lack of thread safety with the dateTimeFormatter
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/JackcessExtractor.java