Please refer to following post on SO:

http://stackoverflow.com/questions/12800531/transactionalreadonly-true-leads-to-lazyinitializationexception

I thought maybe some people here know more about this issue. Currently I'm pretty certain is a bug.

As summary of the SO thread:

Changing a transaction to readOnly (eg. annotate method with @Transactional(readOnly = true)) leads to LazyInitializationException even though the affected relations are fetch eager (eg. FetchType.EAGER). If the method is just annotated with @Transactional, it works perfectly fine.

In the log you can clearly see that hibernate is not doing the same thing and with readOnly = true log is much shorter and the parts were the relatated entites are fecthed is missing, eg. less SQL statements are issued (which of course explains why LazyInitializationException) but it does not explain why does entities are fetched lazy.

Anyone else had this issue? Solution?

I've had some weird experiences like that too, for me, I've 'solved' it by EAGER loading the collection, using the javax.persistence annotations for OneToMany and org.hibernate.annotations CascadeType ALL in a separate tag (not inside the @OneToMany).
I don't know if it'll work for you though. I'm using 3.6.9.Final btw.