How I can get a refresh token to be used for REST API calls to fetch data from atlassian

[Sunil kumar]

I am using Webhook to get data from JIRA to our app. But there are some scenarios where I am not getting data from webhooks. So I have decided to use the REST APIs as well.

Now when I am trying to get a refresh token as per the documentation which says to pass a refresh token inside the POST request  '/oauth/token', But I don't get the refresh token from this endpoint.

I’ve added 

'grant_type' => 'authorization_code',

'client_id' => myclientId,

'client_secret' => myclientSecret,

'code' => authorization-code-received,

'redirect_uri' => myredirectUri,

to the request  and post URL is  https://auth.atlassian.com/oauth/token

The response I am getting is

[access_token] => xxxxxxxxxxxxxxxxxxx
    [expires_in] => 3600
    [token_type] => Bearer
    [scope] => manage:jira-project manage:jira-configuration manage:jira-data-provider read:jira-work manage:jira-webhook write:jira-work read:jira-user

Please let me know if I am doing anything wrong Or what I can do to get the refresh token which could be used for the other API calls later.