@ModelAttribute for form parameter in Spring post handler: is already an attribute?

Question

There's this Spring behaviour that I can't explain from the documentation.

I have a form, which sends a name parameter. Name is a simple bean with a value property.

The handler looks something like this:

    @PostMapping("/hello")
    public String onSubmit(Name name, Model model) { // 1
//  public String onSubmit(@ModelAttribute Name name, Model model) { // 2
        // .. stuff
        return "helloView";
    }

Whether I add the @ModelAttribute annotation (commented line 2) or not (line 1) doesn't make a difference: both a unit test and a JSP page indicate the name attribute is there.

Is there some default behaviour which automatically forwards incoming attributes (from the form) to the model?

For what it's worth: I can use the annotation to change the attribute name. For example: @ModelAttribute("theName") Name name would no longer provide the attribute under the name key, but instead under the theName key (as you would pretty much expect).