Since s3-plugin 0.6, I've noticed that when adding a new "Archive artifacts to S3" post-build task the new "Storage Class" and "Bucket Region" pulldowns are initially empty.

When the job configuration is saved then re-opened, the pulldowns are populated. Storage Class has defaulted to "Standard" and "Bucket Region" has defaulted to "GovCloud".

This will result in errors about the access key being unknown because GovCloud has a completely isolated authentication setup with different IAM, keys, etc.

After editing a second time to correct the config the plugin works as normal.

The problem also affects configurations upgraded from 0.5.

This is a regression since 0.5.