But the effect is that server-side-encryption cannot be enabled as it is configured and applied by the RestS3Service so the settings are not honored (as maybe true to other settings like proxy configuration values).
Turns out passing the Jets3tProperties to the RestS3Service doesn't solve the problem as the values are ignored by the Synchronize class in JetS3t anyway.
This may be related to another issue.
But the effect is that server-side-encryption cannot be enabled as it is configured and applied by the RestS3Service so the settings are not honored (as maybe true to other settings like proxy configuration values).