Marking event as completed fails silently

When event serialization is misconfigured, it may happen that the serialized_event stored in the event_publication table will have slightly different value than the serialized event used in EventPublicationRepository#markCompleted. As a result, even though the event was processed successfully, it is never marked as processed.

This is a corner case, but since I've run into it, it may happen that others run into this issue too.

Here's the repository that reproduces the issue: https://github.com/maciejwalkowiak/modulith-mark-as-processed-issue

There are two classes to look at and I tried to explain what happens with comments:

• https://github.com/maciejwalkowiak/modulith-mark-as-processed-issue/blob/main/src/main/java/com/example/ModulithMarkAsProcessedIssueApplication.java
• https://github.com/maciejwalkowiak/modulith-mark-as-processed-issue/blob/main/src/test/java/com/example/ModulithMarkAsProcessedIssueApplicationTests.java

Once you run the test, you'll see in logs where's the problem.

I believe EventPublicationRepository#markCompleted should throw an exception if no rows have been updated. This would make our serialization mistake obvious much sooner.