Sergey, Thanks.
I have another closely-related whine in mind. I got into this area because I forgot to add one of the form elements to a form pointed at a function annotated with @Multipart. I had sort of hoped that this would lead, optionally, to a null instead of an exception. I note that Multipart is 'one of ours'. Would you object to my added a boolean flag that maps 'no such part' to null instead of throwing?
