Can't add class for checkbox form-group

[shusharin]

I try:
BootForm::checkbox('Label name', 'field_name')->addGroupClass('some-css-class');
result:

<div class="form-group">
	<div class="col-sm-offset-4 col-sm-8 col-md-offset-4 col-md-8 col-lg-offset-3 col-lg-9">
		<div class="checkbox some-css-class">
			<label>
				<input type="checkbox" name="field_name" value="1">Label name
			</label>
		</div>
	</div>
</div>

• "some-css-class" added in div.checkbox.
  How can i get next result? ("some-css-class" added in div.form-group)

<div class="form-group some-css-class">
	<div class="col-sm-offset-4 col-sm-8 col-md-offset-4 col-md-8 col-lg-offset-3 col-lg-9">
		<div class="checkbox">
			<label>
				<input type="checkbox" name="field_name" value="1">Label name
			</label>
		</div>
	</div>
</div>