When using EAGER fetching in @OneToMany realtionship and @ElementCollection in a related entity, the returned data is multiplied.

Consider following case with a tree like structure:
We have entities A (root), B (nodes) and C (additional data of B).
A has relationship @OneToOne to B.
B has relationship @OneToMany to B and @OneToOne to C.
C has @ElementCollection (a map).

In the B parent entity is a list of B children. If the relationship is eager then elements on the list are multiplied as many times as there are elements in C's @ElementCollection.

Workaround:
If you annotate @OneToMany eager relationship with @org.hibernate.annotations.Fetch(org.hibernate.annotations.FetchMode.SUBSELECT) the problem will not occur.

I will provide Hibernate ORM 5 Test Case shortly.