public byte[] marshall() {
        if (marshall == null) {
            marshall = Utilities.marshallEnhanced(COMMAND, identifier,
                    expiry, deviceToken, payload);
        }
        return marshall.clone();
    }
Returns the binary representation of the message as expected by the
APNS server.

The returned array can be used to sent directly to the APNS server
(on the wire/socket) without any modification.
src/main/java/com/notnoop/apns/EnhancedApnsNotification.java