private function getUniqueName(string $baseType, string $headerName) : string
    {
        if (isset($this->headerIndex[$baseType][$headerName])) {
            $newName = $headerName;
            $i = 0;
            while (isset($this->headerIndex[$baseType][$newName])) {
                $newName = $headerName . '_u' . $i;
                $i++;
            }
            $headerName = $newName;
        }
        $this->headerIndex[$baseType][$headerName] = 1;
        return $headerName;
    }