title: Null value output after clicking submit button
body: <p>I expect to receive the value of the button to a.aaa</p>
  
  <p>but i get null instead</p>
  
  <p>a.aaa needs to be "stackOverflow" string in  [HttpPost]</p>
  
  <blockquote>
    <p>controller code</p>
  </blockquote>
  
  <pre><code> public class DefaultController : Controller
          {
              // GET: Default
              public ActionResult Index()
              {
                  return View();
              }
  
              [HttpPost]
              public ActionResult Index(Class1 a)
              {
                  return View();
              }
          }
  </code></pre>
  
  <blockquote>
    <p>model</p>
  </blockquote>
  
  <pre><code>namespace WebApplication3.Models
  {
      public class Class1
      {
          public string aaa { get; set; }
      }
  }
  </code></pre>
  
  <blockquote>
    <p>view</p>
  </blockquote>
  
  <pre><code>@model WebApplication3.Models.Class1
  
  @{
      ViewBag.Title = "Index";
  }
  
  &lt;h2&gt;Index&lt;/h2&gt;
  @using (Html.BeginForm())
  {
      @Html.AntiForgeryToken()
      @Html.ValidationSummary(true)
       &lt;button type="button" name="aaa" id="aaa" value="stackOverflow"&gt;pressMe&lt;/button&gt;
       &lt;input type="submit" /&gt;
  }
  </code></pre>