public static ResultHolder generateExpiredCertificate() throws Exception
    {
        return generateTestCertificate( null, false, false, 0 );
    }
Instantiates a new certificate of which the notAfter value is a point in time that is in the past (as compared
to the point in time of the invocation of this method).

@return A certificate that is invalid (never null).
xmppserver/src/test/java/org/jivesoftware/openfire/keystore/KeystoreTestUtils.java