Dataflow treating {} in JSON keys as references

This is a sample data where `{}` are present in JSON keys:

```
{
"value": [
{
"@odata.etag": "\"2\"",
"ItemInternalId": "27708",
"ID": 27708,
"Name": "Rakesh",
"{Identifier}":"Recordings%252thismyrecording.wma",
"{IsFolder}": false,
"{Marks}":24
},
{
"@odata.etag": "\"3\"",
"ItemInternalId": "27709",
"ID": 27709,
"Name": "Laddu",
"{Identifier}": "Recordings%2426thismyrecording.wma",
"{IsFolder}": true,
"{Marks}":26
},
{
"@odata.etag": "\"3\"",
"ItemInternalId": "27710",
"ID": 27710,
"Name": "Virat",
"{Identifier}": "Recordings%183thismyrecording.wma",
"{IsFolder}": false,
"{Marks}":16
}
]
}
```

It is showing the wrong data preview after flatten transformation in data flow.


But it is giving proper results when transformed to another sink file.


The issue is with the data preview when `{}` are present in JSON keys.