Locks and Transactions - JCR spec example

[Dominik Klaholt]

Hello,

has anyone else stumbled across the JCR spec example on how to avoid 
lost updates (page 240):

begin
    lock
commit

begin
    do A
    save
    do B
    save
    unlock
commit

The strange thing about this example is that the unlock does not have an 
effect if the transaction rolls back - so whatever is locked stays locked.
Is there any way to ensure that the unlock happens no matter whether the 
transaction commits or rolls back (or is the example just a little 
confusing)?

Thanks
Dominik