code: public double expiresIn(AuthRequest req) {
          String val = tokenStore.get(req.asString());
          return val == null ? Double.NEGATIVE_INFINITY :
                  Double.valueOf(TokenInfo.fromString(val).getExpires()) - clock.now();
      }
docs: /*
  @param req The authentication request of which to request the expiration
  status.
  @return The number of milliseconds until the token expires, or negative
  infinity if no token was found.