Previsouly, the reservation was expecting parameters like: slots_attributes: [{start_at: date, end_at: date, availability_id: number}] Now, the reservation is expecting simpler parameters like: slots_reservations_attributes:[{slot_id: number}]
We need to achieve only one process for all booking, not one for subscription, one for reservations, etc. Moreover we must store one object per invoice_item/payment_schedule_object and stop using Invoice.invoiced or PaymentSchedule.scheduled