Fix typing of `Stripe.V2.Event`

Why?

There were typing issues with the return value of client.v2.core.events.list(). Codegen originally produced Stripe.V2.Event but it wasn't able to find that type, despite it being exported. Ramya manually changed the value to Event, which being in the V2 namespace already, picked the correct one. But, we wanted the codegen output to be correct.

There was also an issue with ApiListPromise. It was pulled from the V2 types so I decided to use the V1 type instead. They're very similar and users won't be interacting directly with them, we think.

What?

codegens a <reference path='../EventTypes.d.ts' /> to make V2.Events explicitly available
manually changes the shape of the relatedObject interface to not nest the data. Without that change, I had to reference relatedObject as thin_event.related_object.related_object
manually change the ThinEvent.related_object to be nullable on the push payload.
(didn't generate a diff here, but) uses V1's ApiListPromise as the list return type instead of the V2 version

Now the full codegen output works out of the box.

Testing

I was working off a local script to ensure this was free of type errors. Create a new folder and run:

npm init -y
touch index.ts

Then, paste the following into index.ts:

import { Stripe } from "stripe";

const client = new Stripe("sk_test_1234");

console.log(client);
const thinEvent = client.parseThinEvent("", "", "");
// @ts-expect-error - need to check nullability on id
thinEvent.related_object.id;
// @ts-expect-error - there shouldn't be nesting
thinEvent.related_object.related_object.id;
// this works!
thinEvent.related_object?.id;

const doWork = async () => {
  const events = await client.v2.core.events.list({ object_id: "asdf" });

  const e = events.data[0];

  if (e.type === "v1.billing.meter.error_report_triggered") {
    // related_object is populated!
    console.log(e.related_object.id);
  }
  if (e.type === "v1.billing.meter.no_meter_found") {
    // @ts-expect-error - this event has no related object
    console.log(e.related_object.id);
  }
};

Then, to package the SDK for use, in the local SDK checkout:

npm pack && mv stripe-16.12.0.tgz ~/Desktop

in your created folder:

yarn add ~/Desktop/stripe-16.12.0.tgz
rm yarn.lock && yarn cache clean && yarn install --force

(only repeat the second line if you need to check local changes)

stripe / stripe-node