Exclusion of `network_id`, `vpc_id` and `zone_id`

builtin/providers/cloudstack/resource_cloudstack_ipaddress.go

@@ -155,9 +155,19 @@ func verifyIPAddressParams(d *schema.ResourceData) error {
 	_, vpc := d.GetOk("vpc_id")
 	_, zone := d.GetOk("zone_id")
 
-	if (network && vpc) || (!network && !vpc && !zone) {
+	f := func(bs ...bool) int {
+		cnt := 0
+		for _, b := range bs {
+			if b {
+				cnt++
+			}
+		}
+		return cnt
+	}
+
+	if f(network, vpc, zone) >= 2 || (!network && !vpc && !zone) {
 		return fmt.Errorf(
-			"You must supply a value for either (so not both) the 'network_id' or 'vpc_id' parameter")
+			"You must supply one value for either (so not more than two) the 'network_id' or 'vpc_id' or 'zone_id'  parameter")
 	}
 
 	return nil