SubnetMapping
import type { SubnetMapping } from "https://aws-api.deno.dev/v0.4/services/networkfirewall.ts?docs=full";
The ID for a subnet that you want to associate with the firewall. This is used with "CreateFirewall" and "AssociateSubnets". Network Firewall creates an instance of the associated firewall in each subnet that you specify, to filter traffic in the subnet's Availability Zone.