[P-276] of EJB3 In Action Book states:
"In a bidirectional relationship, the owning side is the entity that stores the relationship in its underlying table."
I guess by relationship it means the Foreign Key. If this is the case, then in @PrimaryKeyJoinColumn, BillingInfo will
be the owning entity and hence the mappedBy should be defined for User.billingInfo field?
[P-277] of EJB3 In Action Book:
What about bidirectional OneToOne using @PrimaryKeyJoinColumn? Does it uses mappedBy property of @OneToOne annotation?