Processor to tag an existing S3 object

A common use case for data aggregation projects is to use AWS S3 as data staging zone. Files are uploaded to S3 buckets from various sources, and NiFi is used to fetch the S3 objects and perform additional processing.

AWS S3 lifecycle management policies allow transitioning S3 objects from standard storage to glacier storage for cost savings in long-term storage. A lifecycle management rule can be set to transition an object that has a particular tag. 

Currently, the only way to tag an S3 object via NiFi is to through the PutS3Object processor. For the above use case, where an S3 object was uploaded by a second- or third-party, it would be very helpful to have a TagS3Processor that can tag an existing S3 object, so that the s3 lifecycle management policy can be triggered after NiFi has processed the S3 object.