Define this parameter in the Http Request Header
{ "OrderNumber": 1, "ReturnRequestItems": [ { "OrderLineNumber": 64, "ReturnQty": 2, "ReturnReason": "sample string 3", "ReturnDescription": "sample string 4" }, { "OrderLineNumber": 64, "ReturnQty": 2, "ReturnReason": "sample string 3", "ReturnDescription": "sample string 4" } ] }