Entities/Administrators/Model/AdministratorsEntityMapper.php
private function getAdministratorsArrayKeyForId(array $administratorsArray, int $id): ?int 
    {
        foreach ($administratorsArray as $key => $administrator) {
            if ($administrator['id'] == $id) {
                return $key;
            }
        }

        return null;
    }
private function getAdministratorsArrayKeyForId(array $administratorsArray, int $id): ?int 
    {
        foreach ($administratorsArray as $key => $administrator) {
            if ($administrator['id'] == $id) {
                return $key;
            }
        }

        return null;
    }
/* returns key of results array for matching 'id' key, null if not found
note, careful when checking return value as 0 can be returned (evaluates to false)