public function add($name, $value)
    {
        $s = $this->getNormalizedHeaderName($name);
        $this->headers[$this->nextIndex] = [ $name, $value ];
        $this->headerObjects[$this->nextIndex] = null;
        if (!isset($this->headerMap[$s])) {
            $this->headerMap[$s] = [];
        }
        array_push($this->headerMap[$s], $this->nextIndex);
        $this->nextIndex++;
    }