Find out the structure of fields for webhooks when using "includeFields"

Hi everyone!

I’m trying to receive info regarding user’s successful subscription to my app, for that I listen at the webhook and specify fields I want to receive like this:

includeFields: [“app_subscription.currency”, “app_subscription.admin_graphql_api_id”, “app_subscription.created_at”, “app_subscription.updated_at”, “app_subscription.lineItems.plan.pricingDetails.AppRecurringPricing.interval”, “app_subscription.name”, “app_subscription.status”]

What I keep getting is this:
payload: {
app_subscription: {
currency: ‘USD’,
admin_graphql_api_id: ‘gid://shopify/AppSubscription/35187032427’,
created_at: ‘2025-02-13T20:31:46-05:00’,
updated_at: ‘2025-02-13T20:37:25-05:00’,
name: ‘Pro’,
status: ‘CANCELLED’
}
}

Problem is, I am looking at the appSubscription object schema and it’s very different from what I’m getting at my webhook. I ask for some fields and they are not there. Other fields such as “admin_graphql_api_id” have different names (in the schema in docs it’s called “id”), and some have different nesting, for example currency should be called “currencyCode” and should be nested in appSubscription.lineItems.Plan.pricingDetails.AppRecurringPricing.price.currencyCode

Where can I find the structure for what I can and cannot receive via this webhook subscription?

Specifically I would like to receive the “interval” field to know if user purchased ANNUAL or EVERY_30_DAYS subscription.