public static List<HostName> parseHostList(String hostString) {
        
        List<HostName> addressList = new ArrayList<>();
        
        if (hostString == null || hostString.isEmpty())
            return addressList;
        
        // First split the string by semicolons and process each entry
        for (String host : hostString.split(";")) {
            
            HostName hostName = new HostName(host);
            try {
                hostName.validate();
                addressList.add(hostName);
            }
            catch (HostNameException e) {
                LOGGER.warn("Invalid host name or IP: {}", host);
                LOGGER.debug("HostNameException.", e.getMessage());
            }
            
        }
        
        return addressList;
        
    }
Parse the provided string into a List of HostName objects, validating
that each item is an IP address, subnet, and/or DNS name.

@param hostString
    The string that contains a semi-colon-separated list of items to
    parse.

@return
    A List of HostName objects parsed from the provided string.
extensions/guacamole-auth-restrict/src/main/java/org/apache/guacamole/host/HostRestrictionParser.java