Refresh Token and Custom Attributes

[#1]

If I read the documentation of GetOAuthV2Info it looks like there is a way to retrieve custom attributes with refresh token. For example the output of the GetOAuthV2Info according to doco is as follows

oauthv2refreshtoken.{policy_name}.access_token
oauthv2refreshtoken.{policy_name}.refresh_token
oauthv2refreshtoken.{policy_name}.client_id
oauthv2refreshtoken.{policy_name}.refresh_count
oauthv2refreshtoken.{policy_name}.organization_name
oauthv2refreshtoken.{policy_name}.refresh_token_expires_in
oauthv2refreshtoken.{policy_name}.refresh_token_issued_at
oauthv2refreshtoken.{policy_name}.refresh_token_status
oauthv2refreshtoken.{policy_name}.developer.email
oauthv2refreshtoken.{policy_name}.developer.id
oauthv2refreshtoken.{policy_name}.developer.app.name
oauthv2refreshtoken.{policy_name}.developer.app.id
oauthv2refreshtoken.{policy_name}.{custom_attribute_name}

My question is how do I assign a custom attribute to a refresh token . I need to assign custom variables to refresh token and retrieve them before generating an access token in exchange of a refresh token.

Please help. Thanks.