问自定义验证的返回值为true区，但不显示错误样式和消息。

EN

<div class="col-md-4">
  <form>
    <div class="form-group has-feedback">
      <select id="variationType[]" name="variationType[]" class="multiple-select form-control" data-minselected="1" data-placeholder="Select one or more options" multiple required>
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="4">Option 3</option>
        <option value="8">Option 4</option>
      </select>
      <small class="help-block with-errors"></small>
      <span class="form-control-feedback" aria-hidden="true"></span>
    </div>

    <button class="btn btn-primary btn-block">Valid</button>
  </form>
</div>

$('.multiple-select').multiselect({
  buttonContainer: '<div class="multiselect-group"></div>',
  buttonClass: 'form-control',
  nonSelectedText: !$(this).attr('data-placeholder') ? 'Selecionar' : $(this).attr('data-placeholder'),
  numberDisplayed: 1
});

$.fn.validator.Constructor.INPUT_SELECTOR = ':input:not([type="submit"], button):enabled';
$('form').validator({
  delay: 200,
  focus: false,
  feedback: {
    success: 'glyphicon glyphicon-ok-sign',
    error: 'glyphicon glyphicon-exclamation-sign'
  },
  custom: {
    minselected: function($el) {
            console.log(!!$.trim($el.val()));
      return !!$.trim($el.val());
    }
  },
  errors: {
    minselected: "Select one or more options"
  }
});