Rule Definition
If the Hibernate application is on different systems that are not time-synchronized, the timestamp generated by each system might be different thereby generating improper optimistic lock success or failures. If your timestamp data type doesn't include a daylight saving time attribute, you'll run into problems with Hibernate's automatic versioning. The version property is less problematic for automatic versioning; hence we recommend it.

Remediation
Use version attribute as a control.

Violation Code Sample

Sample 1
<class name="Sample" table="SAMPLE">
   <id ...../>
   <timestamp name="lastUpdated" column="LAST_UPDATED"/> // VIOLATION
...
</class>
--------------------------------------
Sample 2

//Timestamping is automatically used if you the @Version annotation on a Date or Calendar
@Entity
public class Flight implements Serializable {
...
    @Version //Violation
    public Date getLastUpdate() { ... }
}

or 

@Entity(name = "Person")
public static class Person {

    @Id
    private Long id;

    private String firstName;

    private String lastName;

    @Version                    //Violation
    @Source(value = SourceType.DB)
    private Date version;
}
--------------------------------------------------------------------------------------------

Fixed Code Sample

Remdiation 1
<class name="Sample" table="SAMPLE">
   <id ...../>
   <version name="version" column="VERSION"/> // FIXED
...
</class>

------------------------------------------------
Remediation 2

@Entity(name = "Phone")
public static class Phone {

    @Id
    private Long id;

    @Column(name = "`number`")
    private String number;

    @Version //Fixed
    private Long version;
}

Hibernate in Action (ISBN 1932394-15-X) p 169 and 391