InvalidLambdaresponse : While calling a Java Handler sitting behind an ALB

Question

I'm trying to invoke a Lambda (Java 8) using a DNS endpoint --> ALB --> Lambda as the target group. 
Lambda does what its supposed to do (Upload a file in S3) upon its invocation but on the postman or curl command i see a 502 error . When i check the ALB logs it says InvalidLambdaResponse

My lambda is returning a Map (String , Object). When i print the JSON it looks good as well. What am i missing here ?

{
    "headers": {
        "Cache-Control": "no-store",
        "Content-Type": "application/json"
    },
    "isBase64Encoded": "False",
    "statusCode ": "200",
    "statusDescription ": "200 OK",
    "body": "Lambda S3 Upload"
}

Accepted Answer

It looks like there are a few small errors in the format of the object you're returning. There are some additional spaces in some of the keys (might just be an effect of copy and paste), `isBase64Encoded` should be boolean, and `statusCode` should be an integer.
https://docs.aws.amazon.com/elasticloadbalancing/latest/application/lambda-functions.html#respond-to-load-balancer

This slightly modified version seems to work:
```
{
  "headers": {
    "Cache-Control": "no-store",
    "Content-Type": "application/json"
  },
  "isBase64Encoded": false,
  "statusCode": 200,
  "statusDescription": "200 OK",
  "body": "Lambda S3 Upload"
}
```

InvalidLambdaresponse : While calling a Java Handler sitting behind an ALB

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