curl --request POST \
  --url https://payments.oaknetwork.org/api/v1/merchant/token/refresh \
  --header 'Content-Type: application/json' \
  --data '
{
  "refresh_token": "<string>"
}
'

{
  "msg": "<string>",
  "data": {
    "accessToken": "<string>",
    "refreshToken": "<string>"
  }
}