spring:bind create new (or use default) if null

[Jimmy]

I'm using <spring:bind> to bind to a formBackingObject. However, one
of the value in this object (command) may contain null value. Should
I explicit assign it's contained field to some not-null value (inside
method formBackingObject)? Or there's a way I can detect and create
if null right inside the jsp?

Thanks for input,
Jimmy