Fynd API giving null response

While placing order on jio mart , am getting order event as well as shipment event data . But If I wanted to verify my shipment details using fynd Api like below

OrderPlatformModels.ShipmentInfoResponse shipmentDetails = platformClient.order.getShipmentById(null, shipmentId);

Its giving null response , with status code 200 OK.
Am using fdk-client-java . 1.3.4 version .

As discussed, when am hitting my API , its hitting Fynd also.

APi response :

{
“message”: “”,
“success”: true,
“shipments”: []
}

Hi @manas1.dhal could you please share the shipment id.