Sbt-native-packager doesn't follow folders symlinks during packageZipTarball

Hi! I have an universal folder in resources that contains conf folder:

└── universal
    ├── conf
    │   ├── akka.conf -> ../../main/resources/akka.conf
    │   ├── common.conf -> ../../main/resources/common.conf
    │   ├── local -> ../../main/resources/local/
    │   ├── logback-appenders.xml -> ../../main/resources/logback-appenders.xml
    │   ├── mailer.conf -> ../../main/resources/mailer.conf
    │   ├── mongo.conf -> ../../main/resources/mongo.conf
    │   ├── production -> ../../main/resources/production/
    │   ├── spray.conf -> ../../main/resources/spray.conf
    │   └── staging -> ../../main/resources/staging/
    └── start.sh

As you can see, the most of the files are just symlinks to other place. The problem is that when I build package, all files are copied, but folders are copied without their content (not recursively). So in final build I have something like that:

├── conf
│   ├── akka.conf
│   ├── common.conf
│   ├── local <-- empty!
│   ├── logback-appenders.xml
│   ├── mailer.conf
│   ├── mongo.conf
│   ├── production <-- empty!
│   ├── spray.conf
│   └── staging <-- empty!

If I have simple folders (not a symlink) it works fine. So seems like it doesn't follow symlinks till the end.

Expected behaviour

universal:packageZipTarball should copy all reachable files recursively (including symlinks)

Actual behaviour

universal:packageZipTarball copies symlink as an empty directory

Information

• What sbt-native-packager are you using: 1.3.5
• What sbt version: 1.1.6
• What is your build system (e.g. Ubuntu, MacOS, Windows, Debian ): MacOS 10.13.5
• What package are you building (e.g. docker, rpm, ...): tar
• What version has your build tool (find out with e.g. rpm --version): bsdtar 2.8.3 - libarchive 2.8.3