Message Title

Basically, we need to disable the collection fetching mechanism and override its mechanism like in the following result set transformer example:

Node root = (Node) doInHibernate(session -> {
    return session
        .createSQLQuery(
                "SELECT * " +
                "FROM Node " +
                "CONNECT BY PRIOR id = parent_id " +
                "START WITH parent_id IS NULL ")
        .addEntity(Node.class)
        .setResultTransformer(new ResultTransformer() {
            @Override
            public Object transformTuple(Object[] tuple, String[] aliases) {
                Node node = (Node) tuple[0];
                if(node.parent != null) {
                    node.parent.addChild(node);
                }
                return node;
            }

            @Override
            public List transformList(List collection) {
                return Collections.singletonList(collection.get(0));
            }
        })
        .uniqueResult();
});

This requires some modifications in the hibernate-core because this cannot work if the children association is a @OneToMany association, as it will trigger an additional query upon being traversed.