r275169 made it so that `paymentMethodType` is no longer `required` so that `additionalShippingMethods` can be specified without having to limit it to a specific payment method type. While this works in theory, WebKit doesn't know about the user's selected payment method type until the user actually selects a payment method, meaning that until then the `additionalShippingMethods` are not used, and unfortunately (until now) `PKPaymentRequestPaymentMethodUpdate` did not support providing a `NSArray<PKShippingMethod *> *`, meaning that there was no way to update the list of shipping methods when the user changed their selected payment method, meaning that WebKit would have to wait/rely on the user to change their shipping address _after_ selecting a payment method in order for `additionalShippingMethods` to take effect.
<rdar://problem/81190366>
Created attachment 434560 [details] Patch
Committed r280459 (240094@main): <https://commits.webkit.org/240094@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 434560 [details].