Rename application_fee to application_fee_amount on PaymentIntent

[remi-stripe]

We are renaming application_fee to application_fee_amount as a parameter and property. This is cleaner as application_fee usually is an Application Fee id and can be expanded.

We have confirmed no Java users have used this parameter yet so while a breaking change we can merge and release as the change is being deployed.

r? @brandur-stripe @ob-stripe
cc @stripe/api-libraries
cc @michelle-stripe @ln-stripe

[brandur-stripe]

LGTM.

[brandur-stripe]

We have confirmed no Java users have used this parameter yet so while a breaking change we can merge and release as the change is being deployed.

Just for clarity: are you okay with it if I just release this now? (It seems unlikely that this feature will pick up any new users between now and when the change is deployed to the API.)

[remi-stripe]

@brandur-stripe yeah for once I would just merge early since the change is being deployed to prod soon! Thank you for the quick review.
Also, at worst the bug is that they can't see the app fee on the resource and since it's a beta, they would just ask why and we could explain quickly.

[brandur-stripe]

Also, at worst the bug is that they can't see the app fee on the resource and since it's a beta, they would just ask why and we could explain quickly.

Yep, agreed. Okay, thanks!

[brandur-stripe]

Released as 5.50.0.