public int
getRcode() {
	int rcode = header.getRcode();
	OPTRecord opt = getOPT();
	if (opt != null)
		rcode += (opt.getExtendedRcode() << 4);
	return rcode;
}
Returns the message's rcode (error code).  This incorporates the EDNS
extended rcode.
src/main/java/core/org/xbill/DNS/Message.java