FYI: additional commit for WICKET-6662

[Andrea Del Bene]

Hi,

today I've noted that using version 9.0.0-M2-SNAPSHOT led to a constant 
usage of CPU from task ModificationWatcher. I've spotted a silly line of 
code I wrote for WICKET-6662. Since no one opened an issue for it I 
directly committed the fix. Hope is not a problem.