public Record []
expand() throws IOException {
	List list = new ArrayList();
	for (long i = start; i < end; i += step) {
		String namestr = substitute(namePattern, current);
		Name name = Name.fromString(namestr, origin);
		String rdata = substitute(rdataPattern, current);
		list.add(Record.fromString(name, type, dclass, ttl,
					   rdata, origin));
	}
	return (Record []) list.toArray(new Record[list.size()]);
}
Constructs and returns all records in the expansion.
@throws IOException The name or rdata of a record was invalid after
substitutions were performed.
src/main/java/core/org/xbill/DNS/Generator.java