curl --request POST \
  --url http://{defaultHost}/api/v2/platform/adjustments \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "adjustment": {
    "order_id": "<string>",
    "label": "Shipping costs",
    "adjustable_id": "<string>",
    "adjustable_type": "Spree::LineItem",
    "source_id": "<string>",
    "source_type": "Spree::TaxRate",
    "amount": 10.9,
    "mandatory": true,
    "eligible": true,
    "state": "closed",
    "included": true
  }
}
'

{
  "data": {
    "id": "5",
    "type": "adjustment",
    "attributes": {
      "source_type": "Spree::TaxRate",
      "adjustable_type": "Spree::LineItem",
      "amount": "100.0",
      "label": "Shipping",
      "mandatory": null,
      "eligible": true,
      "created_at": "2022-11-08T19:33:54.527Z",
      "updated_at": "2022-11-08T19:33:54.527Z",
      "state": "open",
      "included": false,
      "display_amount": "$100.00"
    },
    "relationships": {
      "order": {
        "data": {
          "id": "7",
          "type": "order"
        }
      },
      "adjustable": {
        "data": {
          "id": "1",
          "type": "line_item"
        }
      },
      "source": {
        "data": null
      }
    }
  }
}