protected function _getItemClassName($plugin, $aliasClass)
    {
        if ($plugin === null) {
            $plugin = 'Core';
        }

        $buttonClass = $plugin . '.' . self::CLASS_NAME_PREFIX . $aliasClass;
        $className   = App::className($buttonClass, self::CLASS_TYPE);

        if ($className === false) {
            $buttonClass = self::CLASS_NAME_PREFIX . $aliasClass;
            $className   = App::className($buttonClass, self::CLASS_TYPE);
        }

        return $className;
    }