String 
optionToString() {
	StringBuffer sb = new StringBuffer();
	sb.append(address.getHostAddress());
	sb.append("/");
	sb.append(sourceNetmask);
	sb.append(", scope netmask ");
	sb.append(scopeNetmask);
	return sb.toString();
}
Returns the IP address of the client.
src/main/java/core/org/xbill/DNS/ClientSubnetOption.java