protected function getRequestHeaders(EndpointInterface $endpoint): array
    {
        $result = [
            'Accept' => 'application/json',
            'Accept-Language' => $this->options->getLocale(),
            'Content-Type' => 'application/json',
        ];
        if ($endpoint->requiresAuthorizationToken()) {
            $result['Authorization'] = 'Bearer ' . $this->requestAuthorizationToken();
        }
        return $result;
    }