How to add references to rate requests from Magento

As a developer, you want to add reference numbers to the rate requests.

ANSWER

In Magento 2+, in app/code/ShipHawk/Shipping/Model/Carrier.php, the collectRates method gathers all the rates information and sends requests to ShipHawk. As a developer, you can add reference numbers to the rate requests.

Code example:

"reference_numbers" : [{
    "code":   "purchase_id",
    "name":   "Purchase Order #",
    “value:   "P099"
    },
    {
    "code":   "reference_id"
    "name":   "Shipper's Order #",
    "value":  "Test99"
    }
    
    ...

(Forms a regular rate request we can reference to regular ShipHawk API rate requests api/v4/rates.)

See https://docs.shiphawk.com/#rate-request-object.