Parsing XML documents in IzPack is currently incomplete. Even though the XML syntax is well-formatted, there are not recognized bad element or attribute names, thus using the IXmlElement is error-prone especially for typos. Parsing the installation descriptor (install.xml) and several XML resources could be migrated to a different approach.
Best choices might be:
There is a good comparison available for both: How Does JAXB Compare to XStream?