public static Zone from(String zoneString) {
        String[] parts = zoneString.split("\\.");
        if (parts.length != 2)
            throw new IllegalArgumentException("A zone string must be on the form [environment].[region], but was '" + zoneString + "'");

        Environment environment;
        try {
            environment = Environment.valueOf(parts[0]);
        }
        catch (IllegalArgumentException e) {
            throw new IllegalArgumentException("Invalid zone '" + zoneString + "': No environment named '" + parts[0] + "'");
        }
        return new Zone(environment, parts[1]);
    }
Creates a zone from a string on the form environment.region

@throws IllegalArgumentException if the given string is not a valid zone
hosted-zone-api/src/main/java/ai/vespa/cloud/Zone.java