akka.stream.alpakka.s3.headers
Documentation: http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingKMSEncryption.html
optional base64-encoded UTF-8 string holding JSON with the encryption context key-value pairs
amazon resource name in the "arn:aws:kms:my-region:my-account-id:key/my-key-id" format.
Documentation: http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingKMSEncryption.html