Improper encoding of request when using standard html form and resource handler

Apparently processing a request coming from a form in a resource handler, without using any piece of javascript to submit the form, doesn't allow to properly process the encoding of the request.
In Change Request I had a standard html form such as:

<form id="titleForm" action="/my/resource/handler/url" method="post">
<input type="hidden" name="change" value="settitle"/>
<input type="text" id="newTitle" name="newTitle" value="中文"/>
<input type="submit" value="Click me"/>
</form>

When submitted to the resource handler the value of the newTitle parameter was badly encoded when using tomcat. However, when transforming my code to rely on a piece of jQuery with a script as dumb as:

event.preventDefault();
      var actionUrl = $('#titleForm').attr('action');
      $.post(actionUrl, {
        'changeType': 'settitle',
        'new-title': $('input#newTitle').val()
      }).done(function (data) {
        console.log(data);
      });

Then the parameter was properly encoded. Analysis of the request shown that in first case (standard html form) the Content-Type header was application/x-www-form-urlencoded while in second case it was application/x-www-form-urlencoded; charset=UTF-8