public function isContentType(string $contentType) : bool
    {
        $thisContentType = $this->getHeader('Content-Type');

        $pos = strpos($thisContentType, ';');

        if ($pos !== false) {
            $thisContentType = substr($thisContentType, 0, $pos);
        }

        return strtolower($contentType) === strtolower($thisContentType);
    }