src/AdminComponent.php
public function getMenuFilesData()
    {
        \Yii::beginProfile('admin-menu');

        if ($this->_menuFilesData !== null && is_array($this->_menuFilesData)) {
            return (array)$this->_menuFilesData;
        }

        $paths[] = \Yii::getAlias('@common/config/admin/menu.php');
        $paths[] = \Yii::getAlias('@app/config/admin/menu.php');

        foreach (\Yii::$app->extensions as $code => $data) {
            if ($data['alias']) {
                foreach ($data['alias'] as $code => $path) {
                    $adminMenuFile = $path.'/config/admin/menu.php';
                    if (file_exists($adminMenuFile)) {
                        $menuGroups = (array)include_once $adminMenuFile;
                        $this->_menuFilesData = ArrayHelper::merge($this->_menuFilesData, $menuGroups);
                    }
                }
            }
        }

        foreach ($paths as $path) {
            if (file_exists($path)) {
                $menuGroups = (array)include_once $path;
                $this->_menuFilesData = ArrayHelper::merge($this->_menuFilesData, $menuGroups);
            }
        }

        ArrayHelper::multisort($this->_menuFilesData, 'priority');

        if (!$this->_menuFilesData) {
            $this->_menuFilesData = false;
        }

        \Yii::endProfile('admin-menu');

        return (array)$this->_menuFilesData;
    }
public function getMenuFilesData()
    {
        \Yii::beginProfile('admin-menu');

        if ($this->_menuFilesData !== null && is_array($this->_menuFilesData)) {
            return (array)$this->_menuFilesData;
        }

        $paths[] = \Yii::getAlias('@common/config/admin/menu.php');
        $paths[] = \Yii::getAlias('@app/config/admin/menu.php');

        foreach (\Yii::$app->extensions as $code => $data) {
            if ($data['alias']) {
                foreach ($data['alias'] as $code => $path) {
                    $adminMenuFile = $path.'/config/admin/menu.php';
                    if (file_exists($adminMenuFile)) {
                        $menuGroups = (array)include_once $adminMenuFile;
                        $this->_menuFilesData = ArrayHelper::merge($this->_menuFilesData, $menuGroups);
                    }
                }
            }
        }

        foreach ($paths as $path) {
            if (file_exists($path)) {
                $menuGroups = (array)include_once $path;
                $this->_menuFilesData = ArrayHelper::merge($this->_menuFilesData, $menuGroups);
            }
        }

        ArrayHelper::multisort($this->_menuFilesData, 'priority');

        if (!$this->_menuFilesData) {
            $this->_menuFilesData = false;
        }

        \Yii::endProfile('admin-menu');

        return (array)$this->_menuFilesData;
    }
Scan admin config files
@return array