JSON to CSV conversion for dynamic nested CSV

Hi

I am new to Streamsets and there are many more to learn. I am trying to convert Json to CSV having dynamic Json file. 

Sample Json:

{
    "order":
    [
        {
            "order_id": "100001",
            "customer_id": "1045",
            "order_date": "20180701",
            "ship_date": "20180701",
            "item":
                [
                    { 
                    "product_id": "5001", 
                    "quantity": 1
                    },
                    { 
                    "product_id": "5021", 
                    "quantity": 3
                    },
                    { 
                    "product_id": "3331", 
                    "quantity": 4
                    }
                ]
        },
        {
            "order_id": "100002",
            "customer_id": "1088",
            "order_date": "20180701",
            "ship_date": "20180702",
            "freight": "5.00"
        }
    ]
}

Expected Converted CSV file is:

order.order_id,order.customer_id,order.order_date,order.ship_date,order.freight,order.item.product_id,order.item.quantity
100001,1045,20180701,20180701,,5001,1
100001,1045,20180701,20180701,,5021,3
100001,1045,20180701,20180701,,3331,4
100002,1088,20180701,20180702,5,,

Approach I tried: After reading the Json file used two Field Pivoter (1. /order   2. /order/item) and Field Flattener. I am getting the output in expected csv format when JSON file has all the pivoted fields present. But for sample file as above it is throwing error in Pivoter 2 for second record (Order id=100002) and skipping that record.

Please let me know in case you need any other details for the same. Looking for the help and Thank you in advance.

Regards,

Anjalee