JPA OneToMany : List vs Set

Question

I have two entities: UserAccount and Notification. These have a relationship as shown below.

 public class UserAccount {

    @Id
    @         


        

Answer 1

List: Allows duplicate elements in it.

Set: All elements should be unique.

Now, delete may be happening because you are over-writing element in list, and so when you modify persisted entity of UserAccount type, it is removing the entity which is in list previously.