AWS API Gateway not passing Endpoint request header even after transformation - aws-lambda

Question

I'm trying to pass an Authorization header through API Gateway into a Lambda function. I can see the key in the gateway logs. But, even after I transform the input with the standard script (see below), the Authorization head still doesn't make it to the Lambda function.
Any suggestions on what I'm missing?
API Log excerpt
Endpoint request headers:
{
X-Amz-Date=20220419T143450Z,
x-amzn-apigateway-api-id=?????????,
Accept=application/x-www-form-urlencoded,
User-Agent=AmazonAPIGateway_hhompg4,
Host=lambda.us-east-1.amazonaws.com,
X-Amz-Content-Sha256=??????????????????????????????????????????????????,
X-Amzn-Trace-Id=Root=1-????????-???????????????????,
x-amzn-lambda-integration-tag=abcd-4e32-1234-???????????????, Authorization=*********************************************************************************************************************************************************************************************************************************************************************************************************************************************70cc,
X-Amz-Source-Arn=arn:aws:execute-api:us-east-1:-----------------:asfd/test/POST/,
X-Amz-Security-Token=---------------------------------------// [TRUNCATED]
Method Execution / - POST - Integration Request Transformation script:
{
"method": "$context.httpMethod",
"body" : $input.json('$'),
"headers": {
#foreach($param in $input.params().header.keySet())
"$param": "$util.escapeJavaScript($input.params().header.get($param))"
#if($foreach.hasNext),#end
#end
}
}
event keys arriving to lambda function:
2022-04-19T14:29:34.457Z INFO Object.keys(event) [
'resource',
'path',
'httpMethod',
'headers',
'multiValueHeaders',
'queryStringParameters',
'multiValueQueryStringParameters',
'pathParameters',
'stageVariables',
'requestContext',
'body',
'isBase64Encoded'
]
Object.keys(event.headers)
[
'accept',
'accept-encoding',
'accept-language',
'cache-control',
'content-type',
'Host',
'origin',
'referer',
'sec-ch-ua',
'sec-ch-ua-mobile',
'sec-ch-ua-platform',
'sec-fetch-dest',
'sec-fetch-mode',
'sec-fetch-site',
'sec-fetch-user',
'upgrade-insecure-requests',
'User-Agent',
'X-Amzn-Trace-Id',
'X-Forwarded-For',
'X-Forwarded-Port',
'X-Forwarded-Proto'
]

Answer 1

I was able to see my request header (Authorization) in request headers but the same was not visible in the endpoint request headers. Found that you have to enable the 'Use HTTP Proxy integration' option while setting up the integration point.