Código muy cerdo que permite ver de que jars está cogiendo los parsers XML (Xalan y Xerces)

DebugXalanXerces.java

Transformer processor = null;
DocumentBuilder db = null;
try {
	processor = TransformerFactory.newInstance().newTransformer();
	db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
} catch (Exception e) {}

URL url1 = processor.getClass().getResource("TransformerImpl.class");
URL url2 = db.getClass().getResource("DocumentBuilderImpl.class");

if (url1 != null) {
	System.out.println("XALAN: " + processor.getClass().getName() + "--" + url1.toString());
}
if (url2 != null) {
	System.out.println("XERCES: " + db.getClass().getName() + "--" + url2.toString());
}

if (System.getProperty("javax.xml.soap.MessageFactory") != null) {
	
	System.out.println("javax.xml.soap.MessageFactory: " +
		System.getProperty("javax.xml.soap.MessageFactory"));
}
if (System.getProperty("javax.xml.soap.SOAPConnectionFactory") != null) {
	
	System.out.println("javax.xml.soap.SOAPConnectionFactory: " +
		System.getProperty("javax.xml.soap.SOAPConnectionFactory"));
}