Bootstrap 3 Play Framework Field Constructor

gistfile1.scala

@(elements: views.html.helper.FieldElements)

<div class="form-group @elements.args.get('_class) @if(elements.hasErrors) {has-error}" id="@elements.args.get('_id).getOrElse(elements.id + "_field")">
    <label for="@elements.id" class="col-lg-2 control-label">@elements.label(elements.lang)</label>
    <div class="col-lg-10">
        @elements.input
        @if(!elements.errors.isEmpty) {
            <span class="help-inline">@elements.errors(elements.lang).mkString(", ")</span>
        } else {
            <span class="help-block">@elements.infos(elements.lang).mkString(", ")</span>
        }
    </div>
</div>

It doesn't add the form-control class