EJB 3, OneToMany that Acts As Tree, or Parent Child relationship support?

Question

(Sorry for the RoR reference)
I first searched the forum and found this post that came close, but not exactly what I'm needing since my table doesn't reference the PK:
http://forum.java.sun.com/thread.jspa?forumID=13&threadID=767913
I have a table called Folder that represents a folder hierarchy. It has a 'Path' field and a 'Parent' field, and of course 'ID'. Each Folder knows its parent by the 'Parent' field, which references 'Path', not* 'ID'. Both are Strings.
To find all the children of a Folder, the sql for a PreparedStatment might look something like this (shared for clarity of the situation):
SELECT * FROM Folder
WHERE Parent = ?Question:
What are the proper annotations in EJB 3 / JPA to allow this kind non-primary key parent/child relationship mapping?
Can I specify a named query that handles the logic and then reference it in the OneToMany annotation? Other cool tricks?
Here is what I am trying (no runtime errors, but no results either). (Example simplified)
@Entity
@Table(name = "Folder")
@NamedQueries(value = {@NamedQuery(.......)})
public class Folder implements Serializable {
    @Id
    @Column(name = "ID", nullable = false, updatable = false)
    private Integer folderID;
    @Column(name = "Path", nullable = false)
    private String path;
    @Column(name = "Parent")
    private String parent;
    // v Here's the kicker v
    @OneToMany(cascade={CascadeType.ALL}, fetch=FetchType.EAGER)
    @JoinTable(name="Folder",
        joinColumns={@JoinColumn(name="Parent")},
        inverseJoinColumns={@JoinColumn(name="Path")})
    private List<Folder> children;
    // getters and setters ....
}Thanks!

Answer 1

It looks like the relationship is bi-directional.
Will this work...
// Parent.java
@Entity
public class Parent implements java.io.Serializable {
@Id
public Long parentId;
@OneToMany(cascade=CascadeType.PERSIST,mappedBy="parent")
public Collection<Child> children;
// Child.java
@Entity
public class Child implements java.io.Serializable {
@Id
public Long childId;
@ManyToOne
public Parent parent;  // target of mappedBy
}Then, in your code (a session facade?), you'll create the parent first, create the children, then add the children to the parent. Your code is also responsible for maintaining the reference back to the parent.
Parent p = new Parent();
for(int i=0; i<10; i++) {
  Child c = new Child();
  p.children.add(c);
  c.parent = p;
em.persist(p);