title: Using a Facebook access token as the resource owner credentials in OAuth2.0
body: <p>The OAuth 2.0 specification defines the <a href="https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-26#section-4.3" rel="nofollow noreferrer">Resource Owner Password Credentials Grant Type</a>, which allows the resource owner password credentials (i.e. username and password) to be used directly as an authorization grant to obtain an access token.</p>
  <p>I want to allow a user to 'login via Facebook' on the client instead of providing the credentials directly. The client could then exchange the user's Facebook access token for an access token for the authorization server. Does this scheme fit into the framework of OAuth2?</p>