ys prevent the phenomena P1 and P2.

 <p> In addition, calling a lock of type 
 <code>LockModeType.OPTIMISTIC_FORCE_INCREMENT</code> on a versioned object,
 will also force an update (increment) to the entity's version
 column.

 <p> The persistence implementation is not required to support
 the use of optimistic lock modes on non-versioned objects. When it
 cannot support a such lock call, it must throw the <a href="PersistenceException.html" title="class in javax.persistence"><code>PersistenceException</c