public static function contentType(array $operations)
    {
        return function (callable $handler) use ($operations) {
            return function (
                CommandInterface $command,
                RequestInterface $request = null
            ) use ($handler, $operations) {
                if (!$request->hasHeader('Content-Type')
                    && in_array($command->getName(), $operations, true)
                    && ($uri = $request->getBody()->getMetadata('uri'))
                ) {
                    $request = $request->withHeader(
                        'Content-Type',
                        Psr7\mimetype_from_filename($uri) ?: 'application/octet-stream'
                    );
                }

                return $handler($command, $request);
            };
        };
    }