private static function getExtraConfig(Event $event) : array
    {
        $extra = $event->getComposer()->getPackage()->getExtra();
        return is_array($extra) ? $extra : [];
    }
private static function getExtraConfig(Event $event) : array
    {
        $extra = $event->getComposer()->getPackage()->getExtra();
        return is_array($extra) ? $extra : [];
    }
private static function getExtraConfig ( Event $ event ) : array { $ extra = $ event -> getComposer ( ) -> getPackage ( ) -> getExtra ( ) ; return is_array ( $ extra ) ? $ extra : [ ] ; }
Return Composer extra config, make sure it is an array

@param \Composer\Script\Event $event
@return array
Return Composer extra config make sure it is an array