Recently I enabled bytecode enhancement in an application using hibernate 5.2.17.Final (via maven plugin) .
The only option I use is <enableLazyInitialization>true</enableLazyInitialization> .
After that I noticed an unexpected LazyInitializationException in code that was working fine before the change .
Based on https://docs.jboss.org/hibernate/orm/5.3/userguide/html_single/chapters/pc/BytecodeEnhancement.html I added @LazyToOne(LazyToOneOption.NO_PROXY) on one ManyToOne relationship
This made lazy loading work but now if some code loads the entity without initializing this relationship, passes entity ouside of session scope and then tries to merge it in another session then it ends up with :
org.hibernate.LazyInitializationException: Unable to perform requested lazy initialization [classname] - no session and settings disallow loading outside the Session
Which is a bit weird because the same code without @LazyToOne and bytecode instrumentation returns both entities .
Is this issue known/documented ?

This lazy load exception is triggered by CascadeType.MERGE set in @ManyToOne annotation .

I reproduced the issue with code fetched from latest master and will submit a pull request in a moment .