private static Set<Integer> requirePorts(Set<Integer> ports) {
        Objects.requireNonNull(ports, "ports must be non-null");
        if (ports.isEmpty()) {
            throw new IllegalArgumentException("ports must be non-empty");
        }
        if (!ports.stream().allMatch(port -> port >= 1 && port <= 65535)) {
            throw new IllegalArgumentException("all ports must be >= 1 and <= 65535");
        }
        return ports;
    }
Cloud account of this load balancer
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/lb/LoadBalancerInstance.java