Hibernate generating Oracle queries with "(+)" operator instead join

Question

I have to do some improvements to a legacy project using Hibernate 5.0.9 with Oracle database. I noticed that hibernate are generating queries like that

select a.id, b.id
from a, b
where a.b_id = b.id(+)

instead of

select a.id, b.id
from a left join b on a.b_id = b.id

for a code like this

Criteria criteria = session.createCriteria(A.class, "a");
criteria.createAlias("a.b", "b", JoinType.LEFT_OUTER_JOIN);
criteria = criteria.setProjection(
       Projections.projectionList()
         .add(Projections.property("a.id"))
         .add(Projections.property("b.id"))
  );

criteria.list();

At least for me, the "(+)" is complicated to read. In other project with same Hibernate version, the "joins" are generated normally.

Is this a Hibernate configuration?