return
	}

	if err := claims.populateSessionPolicy(r.Form); err != nil {
		writeSTSErrorResponse(ctx, w, ErrSTSInvalidParameterValue, err)
		return
	}

	duration, err := openid.GetDefaultExpiration(r.Form.Get(stsDurationSeconds))
	if err != nil {
		writeSTSErrorResponse(ctx, w, ErrSTSInvalidParameterValue, err)
		return
	}

	claims[expClaim] = UTCNow().Add(duration).Unix()