Today, I have downloaded Spring Framework 3.2.3.
Now, handleMissingValue is called, even if the @RequestParam attribute required = false!
IMHO, this new behaviour is suboptimal. We have many cases, where an empty string parameter value (which has been converted to null by the property editor) should not be handled as missing parameter (even if required = true)! And I guess that many others who relied on the prior behaviour will be confused, too.