When using BBB servers with recording-ready notifications, they are sometimes sent more than once

User report:
We have publish notifications enabled, which sends us the message letting us know when recordings become available in Moodle. However, every once in a while, we seem to get 3 emails. Most of the time (90%?), we just get the one notification email letting us know, but occasionally we’ll get 3 messages in a row that a recording (the same recording) is available.

Problem:

The recording-ready notification is actually performed by the Moodle plugin but triggered by the BBB Server through a callback request. It turns out that if for some requests the Moodle server responds with a timeout error (even though the plugin processes the messages) that failure leads to some more re-attempts.