How to get a JSON output when execute the below Flux query in postman

Flux Query

from(bucket: "prod_jmeter")
|> range(start: 2020-03-29T07:44:00.341Z, stop: 2054-03-29T07:44:00.341Z)
|> filter(fn: (r) => r["_measurement"] == "requestsRaw")
|> filter(fn: (r) => r["_field"] == "responseTime")
|> group(columns: ["_field"])
|> count()

Steps Followed

Converted the flux query to JSON as below and send in via postman

Request Body as below

{
"from": {
"bucket": "prod_jmeter"
},
"range": {
"start": "2020-03-29T07:44:00.341Z",
"stop": "2054-03-29T07:44:00.341Z"
},
"filter": [
{
"fn": "(r) => r["_measurement"] == "requestsRaw""
},
{
"fn": "(r) => r["_field"] == "responseTime""
}
],
"group": {
"columns": ["_field"]
},
"count": {}
}

Request Headers

Authorization – Token <token_Id>
Accept – application/csv
Content-type – application/json

I am getting the below error message

Error Message

{
"code": "invalid",
"message": "error in query specification while starting program: this Flux script returns no streaming data. Consider adding a "yield" or invoking streaming functions directly, without performing an assignment"
}