@Override
    public boolean isActive() {
        if (session != null) {
            return isSessionValid(session);
        } else {
            return true;
        }
    }
@return The time the token will expire (with a small buffer before the actual expiry included)
stroom-security/stroom-security-common-impl/src/main/java/stroom/security/common/impl/UpdatableToken.java