Message parentMsg = getMessageById(parentID);
Message parentMsg = getMessageById(null, parentID);
    public int getConversationIdFromReferent(MimeMessage newMsg, int parentID) {        try {            // file into same conversation as parent message as long as subject hasn't really changed            Message parentMsg = getMessageById(parentID);            if (parentMsg.getNormalizedSubject().equals(ParsedMessage.normalize(newMsg.getSubject())))                return parentMsg.getConversationId();        } catch (Exception e) {            if (!(e instanceof MailServiceException.NoSuchItemException))                ZimbraLog.mailbox.warn("ignoring error while checking conversation: " + parentID, e);        }        return ID_AUTO_INCREMENT;    }