protected function parseActionCssClasses($classes, $action = null, $renderer = null)
    {
        if ($renderer === null) {
            $renderer = $this->getActionRenderer();
        }

        if (is_string($classes)) {
            $classes = explode(' ', $classes);
        } elseif (!is_array($classes)) {
            $classes = [];
        }
        $classes[] = 'btn';
        $classes[] = 'btn-'.$action['actionType'];
        $classes[] = $this->jsActionPrefix().'-'.$action['ident'];

        return $classes;
    }