lib/plugins/aws/customResources/resources/s3/handler.js/update
function update(event, context) {
  const { Region, AccountId } = getEnvironment(context);
  const { FunctionName, BucketName, BucketConfigs } = event.ResourceProperties;

  const lambdaArn = getLambdaArn(Region, AccountId, FunctionName);

  return updateConfiguration({
    lambdaArn,
    region: Region,
    functionName: FunctionName,
    bucketName: BucketName,
    bucketConfigs: BucketConfigs,
  });
}