@Override
    public boolean isValid() {
        return super.isValid() && (identity == null || identity.isValid());
    }
{@inheritDoc}

<p>If an identity has been asserted by the SAML IdP, this
considers also whether the SAML response asserting that identity has
expired.
extensions/guacamole-auth-sso/modules/guacamole-auth-sso-saml/src/main/java/org/apache/guacamole/auth/saml/acs/SAMLAuthenticationSession.java