public function getRequestHeaders(): array
    {
        $headers = clone $this->headers();

        if (!$headers->headerExists('Content-type')) {
            if ($contentType = $this->getContentType()) {
                if (($charset = $this->getCharset()) && (stripos($contentType, 'charset=') === false)) {
                    $contentType .= "; charset={$charset}";
                }

                $headers->setHeader('Content-type', $contentType);
            }
        }

        return $headers->getHeadersForRequest();
    }