Add migration guide for v14.5.0 (#2536)

* Add migration guide for v14.5.0

* Fix wording

* Add code sample

CHANGELOG.md

@@ -11,6 +11,8 @@
     * Fixes #2463 on Android API level 26 and above
 * [#2483](https://github.com/stripe/stripe-android/pull/2483) Fix formatting of `maxTimeout` value in `Stripe3ds2AuthParams`
 * [#2494](https://github.com/stripe/stripe-android/pull/2494) Support starting 3DS2 challenge flow from a Fragment
+* [#2496](https://github.com/stripe/stripe-android/pull/2496) Deprecate `StripeIntent.stripeSdkData`
+* [#2497](https://github.com/stripe/stripe-android/pull/2497) Deprecate `StripeIntent.redirectData`
 * [#2513](https://github.com/stripe/stripe-android/pull/2513) Add `canDeletePaymentMethods` to `PaymentSessionConfig`
     * `canDeletePaymentMethods` controls whether the user can delete a payment method
       by swiping on it in `PaymentMethodsActivity`

MIGRATING.md

@@ -1,5 +1,40 @@
 # Migration Guide
 
+## Migrating from versions < 14.5.0
+- Changes to `StripeIntent`
+    - `redirectData` is now deprecated.
+
+        If a `PaymentIntent` or `SetupIntent` requires a redirect to authenticate, this information will be in `nextActionData`.
+        However, as before, this action will be handled by the SDK in `Stripe.confirmPayment`/`Stripe.confirmSetupIntent`.
+
+        ```kotlin
+        // before
+        if (intent.redirectData != null) {
+            // requires redirect
+        }
+
+        // after
+        when (intent.nextActionData) {
+            is StripeIntent.RedirectData.RedirectToUrl -> // requires redirect
+        }
+        ```
+    - `stripeSdkData` is now deprecated.
+
+        If a `PaymentIntent` or `SetupIntent` requires 3DS1 or 3DS2 authentication, this information will be in `nextActionData`.
+        However, as before, this action will be handled by the SDK in `Stripe.confirmPayment`/`Stripe.confirmSetupIntent`.
+
+        ```kotlin
+        // before
+        if (intent.stripeSdkData != null) {
+            // requires 3D Secure auth
+        }
+
+        // after
+        when (intent.nextActionData) {
+            is StripeIntent.RedirectData.SdkData -> // requires 3D Secure auth
+        }
+        ```
+
 ## Migrating from versions < 14.0.0
 - Changes to Stripe Error localization
     - All [Stripe Error messages](https://stripe.com/docs/api/errors#errors-message) are now localized