In the stack trace, this message appears:
Caused by: org.jets3t.service.S3ServiceException: S3 Error Message. GET '/' on Host 's3.amazonaws.com' @ 'Fri, 07 Jun 2013 17:10:46 GMT' -- ResponseCode: 403, ResponseStatus: Forbidden, XML Error Message: <?xml version="1.0" encoding="UTF-8"?><Error><Code>AccessDenied</Code><Message>Access Denied</Message><RequestId>XXXXXXXXXXXXXXXXX</RequestId><HostId>XXXXX XXXXXXXXXXXXXXXXXXXXXXXXX</HostId></Error>
I'm not sure why it is requesting '/' on s3.amazonaws.com, unless that is a preliminary step to requesting the specified file from the specified bucket.