In the description in EJB 3.0 JPA spec, section 126.96.36.199, the following query example
FROM Department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1
The spec says this query returns 5 references to the department 1 entity if department 1 has 5 employees.
The same query running with openjpa code, it returns only 1 reference to department 1 entity.