ExecutionContext executionContext = createExecutionContext();
executionContext.setSigner(signer);
executionContext.setCredentials(credentials);
StaxResponseHandler<X> responseHandler = new StaxResponseHandler<X>(unmarshaller);
DefaultErrorResponseHandler errorResponseHandler = new DefaultErrorResponseHandler(exceptionUnmarshallers);
Response<X> res = client.execute(request, responseHandler, errorResponseHandler, executionContext);
return res.getAwsResponse();
}