Spring boot - я использую form.submit (), но HttpServletRequest.getParameter имеет значение null

Question

Это HTML-код:

<div class="box d" >
     <form action="/question.do" id="formsubmit">
           <input type="text"  class="box e"  placeholder="">
           <div class="box f" id="boxff">
               <span id="docnum" >using javascript add function</span> /
               <span id="answer" >using javascript add function</span> /
               <span id="startIndex">using javascript add function</span>
           </div>
           <input type="button" name="formsubmits" class="login login-submit" value="something" onclick="formSubmit();">
      </form>
</div>

Это код Javascript:

function formSubmit()
{
    var form = document.getElementById("formsubmit");
    form.docid= document.getElementById("docnum").innerText;
    form.answer= document.getElementById("answer").innerText;
    form.answerstartindex= document.getElementById("startIndex").innerText;
    form.submit();
}

Это контроллер

@Autowired
private DocumentService documentService;
ModelAndView model = new ModelAndView("main");

@RequestMapping("/question.do")
private ModelAndView questionSubmit(@Valid QuestionVO questionVO, BindingResult result,
                                    RedirectAttributes redirect, HttpServletRequest request, HttpServletResponse response) throws Exception {
    Iterator iter = request.getParameterMap().keySet().iterator();
    while(iter.hasNext())
        System.out.println(iter.next());
    return model;
}

Печать консоли нулевая

form.docid, form.answer, form.answerstartindex в javascript дает желаемый результат.

Как передать результат form.submit в контроллер?