ChunkReqPayloadFields:
    | "link"
    | "tag_set"
    | "num_value"
    | "tracking_id"
    | "time_stamp"
    | "lat"
    | "lon"
    | "image_urls"
    | "weight"
    | "boost_phrase"

The key in the ChunkReqPayload which you can map a column or field from the CSV or JSONL file to.