Test case available here:
https://github.com/apixandru/case-study/tree/master/hibernate-versioning

(I tried creating a standard hibernate test case but i don't know how to create this trigger in h2 and how to create the schema manually from the test.)

I'm using versioning as time stamps generated by the database as described here https://docs.jboss.org/hibernate/orm/5.0/devguide/en-US/html/ch05.html#d5e1309

It all works well until I attach a EntityListener to the entity. After that, it identifies the entity as being modified, which triggers an update on the version.

I think that the (if necessary) in the code below should also include not generating the next version if the database generates the timestamp

// increment the version number (if necessary)
final Object nextVersion = getNextVersion( event );

The EntityUpdateAction does a check but it looks like it is a bit too late at that point since previousVersion was the correct version and the 'persister.getVersion( instance )' call actually gets the wrong version

Object previousVersion = this.previousVersion;
if ( persister.isVersionPropertyGenerated() ) {
  // we need to grab the version value from the entity, otherwise
  // we have issues with generated-version entities that may have
  // multiple actions queued during the same flush
  previousVersion = persister.getVersion( instance );
}