When are class objects extended and why? jpa, spring, sleep, javassist

I am using spring 3.0.6, jpa 2.0, sleep mode 3.6.8. My question is: in what situations is javassist used to create a "proxy" for EntityClass? And what is the reason for this proxy? I have the following Entity:

@Entity
public MyEntity{
..

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "adresseID")
  private Adresse adresse;

  @OneToMany(fetch = FetchType.LAZY, mappedBy = "myEntity")
  private List<Parameter> parameters;

..
}

When I load MyEntity from db, the object class is something like MyEntity __ $$ _ javassist. Why is this done? What for? I think that only the regular MyEntity class can be used here.

To implement lazy loading, we can:

• for @OneToMany - here you can use the PersistenceBag.
• for @ManyToOne - use "enchancedClass" here, for example, the address _ $$ _ javassist

, MyEntity? - ? // ?