Group entity

Group.java

@Entity
@Table(name = "groups")
public class Group implements Identifiable<Long> {
    
    @Id
    @GeneratedValue(generator = "SequencePerEntityGenerator")
    private Long id; // getter
    
    @Column(nullable = false, unique = true)
    private String name; // getter and setter
    
    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "group")
    private Set<User> users = new HashSet<>(); // addUser, removeUser, getReadOnlyUsers
    
    /**
     * A group may only exist with a name.
     */
    public Group(final String name) {
        
        this.name = name;
    }
    
    /**
     * For JPA only.
     */
    protected Group() {}
    
    // hashcode & equals
}