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;

}`

```