code: protected void clearSession (PresentsSession session)
      {
          // remove the session from the username map
          PresentsSession rc;
          synchronized (_usermap) {
              rc = _usermap.remove(session.getAuthName());
          }
  
          // sanity check just because we can
          if (rc == null) {
              log.info("Cleared session: unregistered!", "session", session);
          } else if (rc != session) {
              log.info("Cleared session: multiple!", "s1", rc, "s2", session);
          } else {
              log.info("Cleared session", "session", session);
          }
      }
docs: Called by PresentsSession to let us know that we can clear it entirely out of the system.