This change breaks some of our (admittedly fragile and suboptimal) query result parsing code, here’s an example:

Query query = em.createNativeQuery(sql.toString());
for (Object[] result : query.getResultList()) {
  BigDecimal userId = (BigDecimal) result[15];

If this backwards compatibility break is intentional, my apologies: this report can inded be closed (unless you think that a mention of the change in the migration guide is warranted).