private synchronized Iterator
iterator(boolean data, boolean cycle) {
	int size, start, total;

	total = rrs.size();

	if (data)
		size = total - nsigs;
	else
		size = nsigs;
	if (size == 0)
		return Collections.EMPTY_LIST.iterator();

	if (data) {
		if (!cycle)
			start = 0;
		else {
			if (position >= size)
				position = 0;
			start = position++;
		}
	} else {
		start = total - nsigs;
	}

	List list = new ArrayList(size);
	if (data) {
		list.addAll(rrs.subList(start, size));
		if (start != 0)
			list.addAll(rrs.subList(0, start));
	} else {
		list.addAll(rrs.subList(start, total));
	}

	return list.iterator();
}
Deletes all Records from an RRset
src/main/java/core/org/xbill/DNS/RRset.java