Generating access token and refresh token.

Generating access token and refresh token.


I am unable to generate refresh token using the following data
I am using offline access type as per the documentations but still unable to get refresh token. 



  1. response : {
  2.   "access_token": "1000.4538ac6654ee8f5ef0bc554db5e474fc.d918d24a9f911f******10c2b7******",
  3.   "expires_in_sec": 3600,
  4.   "api_domain": "https://www.zohoapis.in",
  5.   "token_type": "Bearer",
  6.   "expires_in": 3600000
  7. }
Please specify the process how can i get refresh token. Have any changes are made in the API auth flow which is not updated in the documents?