The return type of the SUM function over an Integer type column in the Criteria API has changed from Long to Integer. In the old version, with an explicitly defined return type:
CriteriaQuery<Integer> criteria = builder.createQuery( Integer.class );
the result was of type Integer.

In the case where I defined the query as:
CriteriaQuery<Tuple> criteria = builder.createTupleQuery();
the value in the resulting Tuple was of type Long.

After the upgrade, the return type is Integer in both cases.