Unfortunately the element collection mapping uses bag semantics which is not supported. We describe this in the Mapping Exceptions section inside the Envers documentation. You have a couple options to work around this:

#. Specify a @CollectionId annotation.
#. Specify that the collection is indexed using @OrderColumn.
#. Convert the collection container from List to Set.

The first two essentially add additional elements to the primary key definition that allow each element to maintain uniqueness. The latter is a bit of a special case where Envers will translate the Set into an ordered set implicitly and include a special column in the primary key called SETORDINAL by default. You can see the documentation settings on how to customize the name of this field if you want.