title: SingleLogout doesn’t work when session timeout in SP
body: <p>We have a Spring Java application where we implemented SAML authentication.<br />
  We use this application with HTTP login but also with SAML authentication.
  The HTTP session timeout is configured for each user. Actually, when HTTP session expiring we display a pop-up for the user to logout and redirect to login page.</p>
  <p>In case of SAML authentication we had a problem with SingleLogout. For processing logout we redirect to <em>/saml/logout</em> but in processLogout of  <em>SAMLLogoutFilter</em> the auth is null, so the SingleLogout is not realized. The user is not disconnected from the IDP.<br />
  If the user try to reconnect to IDP after a few hours an error is displayed:</p>
  <blockquote>
  <p>Caused by:  org.springframework.security.authentication.CredentialsExpiredException: Authentication statement is too old to be used with value 2021-08-31T06:56:38.000Z</p>
  </blockquote>
  <p>Do you have any idea how to do a SingleLogout after a session timeout?</p>