Lazy-loading doesn't work with Set

[jblaufuss]

We are using Empire for the ORM layer of our application. We have several entities that have java.util.LinkedHashSet collections that are annotated to be lazy-loading with @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL), however we are observing these entities being eager-loaded in our application despite the annotation.

I have spent some time debugging this, and it appears this is due to the way Empire's javaassist proxies are interacting with the java.util.LinkedHashSet implementation: when the proxies are put into the LinkedHashSet's backing LinkedHashMap, the entity-proxy's hashCode() method is called (from HashMap.hash(Object)), which then triggers the ProxyHandler to load the actual entity data. This can happen recursively, causing an eager load of quite a lot of entities despite the consistent use of FetchType.LAZY.

We found this issue in the develop branch (we pulled it in sometime in early 2016).