if (namespace == null) {
throw new VisitorException("QName '" + qname + "' uses an undefined prefix");
}
// Replace the qname node with a new IRI node in the parent node
ASTURI uriNode = new ASTURI(SyntaxTreeBuilderTreeConstants.JJTURI);
uriNode.setValue(namespace + localName);
qnameNode.jjtReplaceWith(uriNode);
return null;
}