JSON NodeReference help

I have a need to extract some JSON data, my postman data looks as follows postman

JSON

"typeProperties": {

            "format": {

                "type": "JsonFormat",

                "filePattern": "setOfObjects",

                "jsonNodeReference": "$.[0].",

                "jsonPathDefinition": {

                    "firstRecIdField": "firstRecIdField"

                }

            },

But the pipeline is failing with JsobReader item not an object, any ideas on how I should structure it in ADF?

Thanks in advance