Strange code: Declaration of Axiom_Plugin_Updater

Just installed Oshine template and I’m seeing a strange code when I try to upload a graphic to my Media Library:
Warning : Declaration of Axiom_Plugin_Updater::download_package($package, $check_signatures = false) should be compatible with WP_Upgrader::download_package($package, $check_signatures = false, $hook_extra = Array) in /home4/walg6g0agzfu/public_html/wp-content/plugins/masterslider/admin/includes/classes/class-axiom-plugin-updater.php on line 29
108