HHH-5855 was fixed starting Hibernate 5.0.8

Conclusions at the beginning:

1. Update your Hibernate version to the final release.

2. Read A beginner’s guide to Hibernate Set and List behavior by Vlad Mihalcea (especially if update is not an option for you)

Why?

The Hibernate HHH-5855 causes an output like below:

BEFORE Hibernate 5.0.8:

Fire inserts:

Fire updates:

A complete example to play with is available here.

AFTER Hibernate 5.0.8:

Fire inserts:

Fire updates:

A complete example to play with is available here.