This version was used originally used in owlcms2. The binaries for net.sf.jxls are still available on Maven Central. The source was recovered from https://sourceforge.net/projects/jxls/files/jxls/1.0.6/
The new jxls 2.6 version at http://jxls.sourceforge.net/ would require too much work to adapt, so we kept the same code in owlcms4