ContractPreviewModel

{
    "amount": 0,
    "valid": false,
    "fees": {
        "total": 0,
        "covered": true,
        "breakdown": {
            "pct": 0,
            "add": 0,
            "min": 0,
            "max": 0,
            "fixed": 0
        }
    },
    "messages": [
        {
            "code": "string",
            "type": "error",
            "message": "string"
        }
    ]
}