nmrao - Thank you very much for the reply.
After discussing with dev team, i got to know that i have to use Media Type as 'multipart/form-data'.
It will be a great help if you share an example how to write body data dynamically of multipart/form-data.
Below is the payload which i can see in chrome console
------WebKitFormBoundaryx5wcwgn0MRYwf1Z2
Content-Disposition: form-data; name="fileType"
DCA_FILE
------WebKitFormBoundaryx5wcwgn0MRYwf1Z2
Content-Disposition: form-data; name="DCA_FILE"; filename="Orion DCA.csv"
Content-Type: application/vnd.ms-excel
------WebKitFormBoundaryx5wcwgn0MRYwf1Z2
Content-Disposition: form-data; name="projectId"
5a3aa07d8058f37f26f10831
------WebKitFormBoundaryx5wcwgn0MRYwf1Z2
Content-Disposition: form-data; name="columnMapTemplate"
{"mappings":{"make":"deviceType":"","hasColor":"","location":"","country":"","site":"","building":"","floor":"","subEnvId":"","stapleTotalLastReading":"","notes":""},"name":"defaultTemplate"}
------WebKitFormBoundaryx5wcwgn0MRYwf1Z2--
Thanks a lot in advance.