"HSN cannot be empty" while creating invoice using API

"HSN cannot be empty" while creating invoice using API

While Trying to create an Invoice using API in Zoho Books I am facing this error in the response. HSN is an custome field added in items i have included this into my json string but still facing issues.

{
"customer_id":"519558000001375768",
"invoice_number": "QSAI-5641/19-20",
"place_of_supply": "AS",
"gst_treatment": "business_none",
"reference_number": "404-1240743-0546722",
"date": "2019-04-27",
"is_inclusive_tax": false,
"line_items": [
{
"item_id":"519558000002173295",
"product_type": "goods",
"warehouse_id": "519558000000076101",
"sku": "AHD330-1TU31-CBK",
"name": "ADATA HD330 1TB External Hard Drive-Black",
"rate": 3473.72998,
"quantity": 1,
"hsn_or_sac": "8523",
"tax_name": "IGST18",
"tax_type": "tax",
"tax_percentage":18,
"item_custom_fields": [
{
"HSN":"8523"
}
]
}
],
"status":"Closed",
}