private void
nodeToString(StringBuffer sb, Object node) {
	RRset [] sets = allRRsets(node);
	for (int i = 0; i < sets.length; i++) {
		RRset rrset = sets[i];
		Iterator it = rrset.rrs();
		while (it.hasNext())
			sb.append(it.next() + "\n");
		it = rrset.sigs();
		while (it.hasNext())
			sb.append(it.next() + "\n");
	}
}
Returns an Iterator over the RRsets in the zone that can be used to
construct an AXFR response.  This is identical to {@link #iterator} except
that the SOA is returned at the end as well as the beginning.
src/main/java/core/org/xbill/DNS/Zone.java