How to Pass array in json to a body of service integration state by taking input from form state

Summary:

I am working on a use to create a Sales Order in JDEdwards ERP using ODA, where I need to take few mandatory inputs from the user and then pass it to the Service Integration Call (with JSON input in Body ) as below-

{

  "Branch": "${submittedFields.value.MCU}",

  "Ship_To": "${submittedFields.value.ShipTo}",

  "Sales_Order_Detail": [

    {

      "Quantity_Ordered": "${submittedFields.value.Qty}",

      "Item_Number": "${submittedFields.value.item}"

    },

    {

      "Quantity_Ordered": "${submittedFields.value.Qty}",

      "Item_Number": "${submittedFields.value.item}"

    },

]

}

  With this, I am able to create a Order with 1 Line Item, However now my interest is to create a single order for multiple line items. Would like your help to understand, how can i take multiple input from User for Item and Qty to create 1 order of multiple lines with same B/P and ShipTo.