I use React and Node with Passwordless login in my system and would like to learn more about refresh session ('/session/refresh'). Currently, our frontend applications using React automatically make refresh requests, and we want to understand how this request to the Supertokens refresh service works. Another question we have is that when we force a refresh request using the React library, both 'sRefreshToken' and 'sAccessToken' are sent. However, when the refresh request is made automatically, only the 'sRefreshToken' header is sent. Could you explain why the automatic request sends only this header? Additionally, could you clarify which fields are truly mandatory for a successful refresh?