public function get_subplugins_of_plugin($component) {

        $pluginfo = $this->get_plugin_info($component);

        if (is_null($pluginfo)) {
            return array();
        }

        $subplugins = $this->get_subplugins();

        if (!isset($subplugins[$pluginfo->component])) {
            return array();
        }

        $list = array();

        foreach ($subplugins[$pluginfo->component] as $subdata) {
            foreach ($this->get_plugins_of_type($subdata->type) as $subpluginfo) {
                $list[$subpluginfo->component] = $subpluginfo;
            }
        }

        return $list;
    }