public function filterNullValuesFromArray(array $arr): array
    {
        foreach ($arr as $key => $value) {
            if ($value === null) {
                unset($arr[$key]);
            }
            if (is_array($value)) {
                $arr[$key] = $this->filterNullValuesFromArray($value);
            }
        }

        return $arr;
    }