Session session = em.unwrap(Session.class);
org.hibernate.procedure.ProcedureCall call =
    session.createStoredProcedureCall("FIND_ITEMS");

call.registerParameter(1, Object.class, ParameterMode.REF_CURSOR);

org.hibernate.result.ResultSetOutput resultSetOutput =
    (org.hibernate.result.ResultSetOutput) call.getResult().getCurrent();

List<Item> result = resultSetOutput.getResultList();
assertEquals(result.size(), 3);
for (Item item : result) {
    // ...
}

create function FIND_ITEMS() returns refcursor as '
    declare someCursor refcursor;
    begin
        open someCursor for select * from ITEM;
        return someCursor;
    end;' language plpgsql;

org.hibernate.cfg.NotYetImplementedException: Support for REF_CURSOR parameters not yet supported
	at org.hibernate.procedure.internal.AbstractParameterRegistrationImpl.prepare(AbstractParameterRegistrationImpl.java:220)
	at org.hibernate.procedure.internal.ProcedureCallImpl.buildOutputs(ProcedureCallImpl.java:421)
	at org.hibernate.procedure.internal.ProcedureCallImpl.getResult(ProcedureCallImpl.java:375)