public static ResultHolder generateCertificateChainWithExpiredRootCert() throws Exception {
        return generateCertificateChainWithExpiredRootCert(null);
    }
Generates a chain of certificates, identical to {@link #generateValidCertificateChain()}, with one exception:
the last certificate (the root CA) is expired.

@return an array of certificates. Never null, never an empty array.
xmppserver/src/test/java/org/jivesoftware/openfire/keystore/KeystoreTestUtils.java