JPA Entity Mapped as OneToOne as well as OneToMany

Question

Consider the following JPA entity. My application instance class must always have a OneToOne reference to 4 special instances of Envelope but it also has a set of 0-infinite user defined envelopes. Is this even possible? Is it possible with both Unidirectional and/or Bidirectional references?

    @Entity(name = "Application_Instance")
public class ApplicationInstance implements Serializable {

    @Id
    private int databaseId;
    private Envelope accountTransfersEnvelope = new Envelope("Account Transfers");
    @OneToOne
    private Envelope newTransationsEnvelope = new Envelope("New Transactions");
    @OneToOne
    private Envelope incomeEnvelope = new Envelope("Income Envelope");
    @OneToOne
    private Envelope creditCarEnvelope= new Envelope("Credit Card");
    @OneToMany
    protected Set<Envelope> userEnvelopes = new HashSet<Envelope>();

//rest of class
}

Answer 1

You could do this with a join table mapping:

@OneToMany
@JoinTable( name = "USER_ENVELOPE",
            joinColumns = { @JoinColumn( name = "APP_ID" ) },
            inverseJoinColumns { @JoinColumn( name = "ENVELOP_ID" ) } )        
protected Set<Envelope> userEnvelopes = new HashSet<Envelope>();