src/Adapter/ControlsAdapter.php
protected function checked(array $control, array $displayable)
    {
        if (empty($displayable)) {
            return ['checked' => 'checked'];
        }
        foreach ($displayable as $item) {
            if ($control['name'] == $item['name']) {
                return ['checked' => 'checked'];
            }
        }
        return [];
    }
protected function checked(array $control, array $displayable)
    {
        if (empty($displayable)) {
            return ['checked' => 'checked'];
        }
        foreach ($displayable as $item) {
            if ($control['name'] == $item['name']) {
                return ['checked' => 'checked'];
            }
        }
        return [];
    }
verify whether checkbox should be checked

@param array $control
@param array $displayable
@return string