The documentation says:
AlphaHPP can calculate the shopping cart product contents for a merchant.
developer.alphacommercehub.com.au/docs/alphahpp-#product-line-information
What will happen if Amount value differs from the amount calculated from OrderDetails?
Will AlphaHPP reject the payment request, or maybe it will silently give priority to the Amount or the calculated amount?
This question is not so exotic as it seems to be.
The amounts can slightly differs because of some rounding errors.
Magento can use a lot of rules to calculate an order’s grand total: tax rules, shipping rules, discount, currency conversions, and so on.
In my experience, some payment gateways reject a payment transaction if its grand total amount differs from the order lines amount event in 1 cent.
For such gateways I make some adjustments to order lines to make amounts exactly the same (e.g. add a new order line called «adjustment»).
So it is important to know how does AlphaHPP behave in such cases.