public static CidrBlock fromString(String cidr) {
        String[] cidrParts = cidr.split("/");
        if (cidrParts.length != 2)
            throw new IllegalArgumentException("Invalid CIDR block, expected format to be " +
                    "'<ip address>/<prefix size>', but was '" + cidr + "'");

        InetAddress inetAddress = InetAddresses.forString(cidrParts[0]);
        int prefixSize = Integer.parseInt(cidrParts[1]);

        return new CidrBlock(inetAddress, prefixSize);
    }
@return iterable over all CIDR blocks of the same prefix size, from the current one and up
vespajlib/src/main/java/ai/vespa/net/CidrBlock.java