Before diving into the detailed discussion, let's first familiarize ourselves with the model we will be using.
**User Class:**
```java
public class User implements Serializable, Comparable {
protected Long id = null;
private int version;
private String firstname;
private String lastname;
```
Here is a brief overview of the User class:
- The `User` class implements the `Serializable` and `Comparable` interfaces.
- It contains the following fields:
- `id`: A protected field of type `Long`, initially set to `null`.
- `version`: A private field of type `int`.
- `firstname`: A private field of type `String`.
- `lastname`: A private field of type `String`.