Yes, this is a limitation of JSF. It is not possible to validate nullness using a JSF validator. You need to use required=true.
Thanks for answering my post Gavin.
Also could you briefly comment on the @IfInvalid annotation eg. does it still function as expected?
I am asking the question because I think that only the Issues example in the Seam 1.0 GA release uses the @IfInvalid annotation.
Yes, it still works, but I am probably going to deprecate it.