Empty textfield does not update bound bean

I’m not sure if this should be in data binding or UI but here goes:
On a com.vaadin.ui.Form I have a required com.vaadin.ui.Text which is marked as required. I have other fields too.
The form is bound (binded?) to a bean and this all works fine except for one thing.

When I put a value into any of the fields (including the required field) the relevant setter gets called, which is what I expect and is good.
Then, when I clear the required field the setter is
called, which is the problem.
I set a break on the setter to verify this and it doesn’t go there, so my bound bean has the wrong value.
It definitely does go there when I enter something in the field.
Am I missing some step?

Vaadin 6.6.6
Java 6 (java-6-sun-
JBoss 4.2
Ubuntu 11.10

I found the answer to this one myself.
I just had to setInvalidCommitted(true) on the field.
I did this after upgrading to 6.7.4 and I have not gone back to the previous version to check if it was there then.
But this sorts out my problem perfectly.