Should read:
if(item.getMasterSecret() == null || !WirePrefix.isEncryptedMmsSubject(retrieved.getSubject().getString()))

This is to handle the case when the user has not entered their password. If the user has not entered their password or the message is not encrypted then a notification should be shown. Otherwise the notification should be shown once the DecryptingQueue has finished decrypting the message. I could instead call sendXNotification   every time a message is either received or decrypted and then have PebbleNotifier choose whether to send the notification.