i.e., from https://www.pulumi.com/docs/reference/pkg/azure-native/network/applicationgateway/#create-application-gateway, a snippet from the httpListeners array:

httpListeners: [
        {
            frontendIPConfiguration: {
                id: "/subscriptions/subid/resourceGroups/rg1/providers/Microsoft.Network/applicationGateways/appgw/frontendIPConfigurations/appgwfip",
            },
            frontendPort: {
                id: "/subscriptions/subid/resourceGroups/rg1/providers/Microsoft.Network/applicationGateways/appgw/frontendPorts/appgwfp",
            },