Azure Automate ML Model - Error in testing endpoint JSON format

Question

Need help in inputting data to the JSON test endpoint:

Below is the datatype of the fields.

vendor_id=String

rate_code=int

passenger_count=int

trip_time_in_secs=int

trip_distance=decimal

payment_type=String

Error:

Failed to test endpoint

{"message":"POST body could not be decoded as JSON: Expecting ',' delimiter: line 4 column 18 (char 54)"}

Below is the JSON endpoint code.

{
  "input_data": {
    "columns": [
      "vendor_id":"CMT",
      "rate_code":1,
      "passenger_count":1,
      "trip_time_in_secs":1500,
      "trip_distance":3.5,
      "payment_type":"CRD"
    ],
    "index": [],
    "data": []
  }
}