[Filebeat] json unmarshal error in S3 input

[kaiyan-sheng]

There are users seeing this error message or similar when using s3 input:

handleSQSMessage failed: json unmarshal sqs message body failed: invalid character 'd' in literal false (expecting 'a') 

2020-08-26T10:05:10.780Z        ERROR   [s3]    s3/input.go:257 handleSQSMessage failed: json unmarshal sqs message body failed: invalid character 'e' in literal true (expecting 'r')

This issue is to track the process on fixing this issue.

Discuss forum issues:
https://discuss.elastic.co/t/s3-filebeat-input-cloudfront-logs-handlesqsmessage-failed-json-unmarshal-sqs-message-body-failed/239716
https://discuss.elastic.co/t/s3-filebeat-input-error/246654

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)