Nested Customised JSON

[aartijain]

I have a CSV file as follows:
valueType,orderNumber,carrier-skuCode,consignmentNumber
1,3005273498,UKMAIL,31323370270885
2,3005273498,82032838,31323370270885
2,3005273498,82032853,31323370270885
2,3005273498,82032863,31323370270885
2,3005273498,82032870,31323370270885

I would like to generate json file using mETL in below format:
[
{
"orderNumber" : 3005273498,
"consignmentNumber" : 31323370270885,
"orderLines" : [
{"consignmentNumber" : 31323370270885,
"skuCode": 82032838,
"carrierCode": "UKMAIL"
},
{"consignmentNumber" : 31323370270885,
"skuCode": 82032853,
"carrierCode": "UKMAIL"
},
{"consignmentNumber" : 31323370270885,
"skuCode": 82032863,
"carrierCode": "UKMAIL"
},
{"consignmentNumber" : 31323370270885,
"skuCode": 82032870,
"carrierCode": "UKMAIL"
}
]
}
]

Can anyone suggest how can I achieve this?