HTTPMethod is empty

Tried to use the `events.APIGatewayProxyRequest.HTTPMethod` but it returned `""`

Here's the full handler
```go
func Handler(request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
fmt.Println("Received body: ", request.Body)
switch request.HTTPMethod {
case "POST":
return events.APIGatewayProxyResponse{Body: request.Body, StatusCode: 200}, nil
default: // GET
response := events.APIGatewayProxyResponse{
Body: request.QueryStringParameters["value"],
StatusCode: 200,
}
return response, nil
}
}
```