SilverStripe SiteConfig TabSet

SS-SiteConfigTabSet

$set = new TabSet(
            'test tab set',
            new Tab(
                'tab a',
                TextField::create('TabAContent')
            ),
            new Tab(
                'tab b',
                TextField::create('TabABontent')
            )
        );
        $fields->addFieldToTab('Root', $set);