protected function setHeader($name, $value)
    {
        $name  = $this->prepareHeaderName($name);
        $value = $this->prepareHeaderValue($value);

        $normalized = strtolower($name);
        if (! isset($this->headerNames[$normalized])) {
            $this->headerNames[$normalized] = $name;
        }

        $header = $this->headerNames[$normalized];

        $this->rawHeaders[$header] = $value;

        return $this;
    }