post https://api.sandbox.rainforestpay.com/v1/payins//simulate_ach_return
Only available in the Rainforest sandbox environment.
May only be called on an ACH payin in PROCESSING or SUCCEEDED statuses. An ACH return must not have already been created for the payin.
The expected webhooks will be sent as the payin's status is advanced and when the ACH return is created.