WordPress: how to use “do_not_allow” with map_meta_cap in Multisite to restrict custom capability to non-super-admins

custom_capability.php

<?php

function customCapabilityRules($caps, $cap, $user_id, $args)
{
    $deny = array();

    switch ($cap) {
        case 'my_custom_capability':
          if( is_super_admin() ){
            $deny[] = 'my_custom_capability';
          }
          break;
    }

    if (in_array($cap, $deny)) {
        $caps[] = 'do_not_allow';
    }

    return $caps;
}

add_filter('map_meta_cap', 'customCapabilityRules', 10, 4);