Generate Json Structure

I want to create a projection that I can POST the following json.

{
  "InventTrans": {
    "Applicaiton": "It is a Text",
    "ModelCost": [
      {
        "Action": "It is a Text",
        "Division": "It is a Text",
        "ManuxPart": "It is a Text",
        "ManuxCfgId": "It is a Text",
        "Module": "It is a Text",
        "Origin": "It is a Text",
        "TransactionId": "It is a Text",
        "TransactionCode": "It is a Text",
        "PartNo": "It is a Text",
        "Contract": "It is a Text",
        "ConfigurationId": "It is a Text",
        "Direction": "It is a Text",
        "Quantity": "It is a Text",
        "IsoUnit": "It is a Text"
      },
      {
        "Action": "It is a Text",
        "Division": "It is a Text",
        "ManuxPart": "It is a Text",
        "ManuxCfgId": "It is a Text",
        "Module": "It is a Text",
        "Origin": "It is a Text",
        "TransactionId": "It is a Text",
        "TransactionCode": "It is a Text",
        "PartNo": "It is a Text",
        "Contract": "It is a Text",
        "ConfigurationId": "It is a Text",
        "Direction": "It is a Text",
        "Quantity": "It is a Text",
        "IsoUnit": "It is a Text"
      }
    ]
  }
}

I defined my structure as follows,

but when I try to post I am getting the following error. doesnt IFS projection support Lists with POST? or am I missing something?

Thank you,

/Jeewan