src/Publisher.php
private function createBodyForRequest(array $body = []): ?\GuzzleHttp\Psr7\MultiPartStream
    {
        if (empty($body)) {
            return null;
        }
        return new MultipartStream($body);
    }
private function createBodyForRequest(array $body = []): ?\GuzzleHttp\Psr7\MultiPartStream
    {
        if (empty($body)) {
            return null;
        }
        return new MultipartStream($body);
    }
createBodyForRequest