How to specify S3 credentials(secret + key) in StaticS3Firehose

Hello,

I tried to use Index Task to create segment on small Avro files, those files are all stored on S3. When I tried to use StaticS3Firehose, I can not find any example or doc to tell me how to pass the S3 credentials in the StaticS3Firehose. The current StaticS3Firehose specification does NOT have any credential options. So can anybody tell me how to achieve this?

Thanks!