Robocode 1.8.3.0 does not include the .data/[robot package] directory inside the .jar file.
The Robot Packager should automatically check if the .data/[robot package] directory exists. If so. If so, it show show a marked check box that this directory (and ALL files) must be included. If no data directory exists, it should be grayed out. Removing the mark from the check box means that it should not be included - even though it exists.
It seems that folders in the robot data directory is not supported. Hence, this should/could be implemented when fixing this issue.
Fixed in version 1.9.0.0