I created a test which demonstrates the issue:

https://github.com/schauder/bug-hibernate-id-cascading/blob/tuple-alias/orm/hibernate-orm-5/src/test/java/org/hibernate/bugs/JPAUnitTestCase.java

This fails:

Query query = entityManager.createQuery("select one from SomeEntity where id = 23", Tuple.class);

Tuple tuple = (Tuple) query.getSingleResult();

TupleElement<?> element = tuple.getElements().get(0);
assertNotNull(element.getAlias());

Because element.getAlias() returns null although I think it should return the column name "one"

Note that the test does not fail when the query is edited to include an explicit alias: