I got the issue:
The problem was mere syntax issue with my JSON request (had missed commas!).
I corrected it like below and it is working like a charm now:
{
"id": 300999,
"name": "Akshay Lokur",
"designation": "Associate",
"department": "Tech",
"salary": 500000
}
Response:
201 Created
P.S.: We also need to give double quotes to "keys" in JSON!
Yippee :)
Cheers.