public void setTimezone(String timezone) {
        this.timezone = timezone;
    }
Set the string value of the timezone, or null if the timezone will not
be provided by the client.  Valid timezones are specified in IANA zone
key format (aka Olson time zone database or tz database).

@param timezone
    The string value of the timezone reported by the client, in tz
    database format, or null if the timezone is not provided by the
    client.
guacamole-common/src/main/java/org/apache/guacamole/protocol/GuacamoleClientInformation.java