Error during sending a signed http request to ElasticSearch

hey,
I am running into an error while making a httprequest to Elastic Search The error is

> The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method

Following is the code. Any pointers to bug in my code or library would be appreciated.

```
`invocation_response my_handler(invocation_request const& request)
{
ClientConfiguration config;
config.region = Aws::Environment::GetEnv("AWS_REGION");
config.caFile = "/etc/pki/tls/certs/ca-bundle.crt";
auto credentialsProvider = Aws::MakeShared("es");

auto client = CreateHttpClient(config);
auto httpRequest = CreateHttpRequest(URL, HttpMethod::HTTP_GET,
Aws::Utils::Stream::DefaultResponseStreamFactoryMethod);

httpRequest->SetContentType("application/json");

nlohmann::json query1 = {};
query1.emplace("size", 25);

std::shared_ptr sstream = make_shared();
*sstream << query1;
httpRequest->AddContentBody(sstream);
Aws::Client::AWSAuthV4Signer signer(credentialsProvider, "es", config.region);
auto req = httpRequest.get();
signer.SignRequest(*req);
auto outcome = client->MakeRequest(httpRequest);
if (outcome->GetResponseCode() == HttpResponseCode::OK) {
cout << "SUCCESS" << endl;
} else {
// print the response from the http request
cout << "ERROR" << endl;
cout << outcome->GetResponseBody().rdbuf() << endl;
cout << outcome->GetResponseCode() << endl;

}`

```

从 issue 中所示的请求构造和 Aws::Client::AWSAuthV4Signer::SignRequest 调用开始，然后使用已配置的区域和环境凭证向 Elasticsearch 重现该请求。将签名输入与服务响应进行比较；确认库缺陷并提供最小复现，或记录对调用方设置的修正，即表示完成。

由索引模型根据 Issue 内容生成。