API Gateway CORS: How to get path and body into AWS Lambda? - aws-lambda

Question

I am having trouble getting the path and body into an AWS Lambda using AWS API Gateway. It works on Chrome with security disabled, but once I deploy the front end to S3, the path and body do not show up in the event that is sent to the Lambda. Here is the log from when I send locally:
And here is the log from when I send it with Chrome security enabled:
With Chrome security enabled, I get the following response:
"Access to XMLHttpRequest at 'https://1jlcspd2re.execute-api.us-east-1.amazonaws.com/genecab-bracket-optimizer' from origin 'http://www.genecab.com.s3-website-us-east-1.amazonaws.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status."
The JSON payload looks the same on both requests. Here are the headers and payload from when I send with Chrome security disabled:
And with Chrome security enabled:
I have the following CORS configuration on the AWS API Gateway:
Any help would be appreciated.

Answer 1

After searching extensively, I discovered that I have to return an Access-Control-Allow-Origin header when the httpMethod=OPTIONS on the request. Here is my java code:
MyLambdaResponse lambdaResponse = new MyLambdaResponse();
Map<String, String> headers = new HashMap<>();
headers.put("Access-Control-Allow-Origin", "*");
lambdaResponse.setHeaders(headers);
if (input!=null) {
if(input.toString().contains("httpMethod=OPTIONS")) {
return lambdaResponse;
}
}