protected function applyRequestHeaders(array $curl_options = []): array
	{
		$headers = $this->getHeaders();

		if (empty($headers))
		{
			return $curl_options;
		}

		$set = [];

		foreach ($headers as $name => $value)
		{
			$set[] = $name . ': ' . $this->getHeaderLine($name);
		}

		$curl_options[CURLOPT_HTTPHEADER] = $set;

		return $curl_options;
	}