Fixing by upgrading to newer version of Shadowjar / Gradle

Hello Ben!

This is a great example but I had some problems getting it to work. It kept failing for me as follows:

    $ ./gradlew shadow

    FAILURE: Build failed with an exception.

    * What went wrong:
    A problem occurred configuring root project 'docker-service-discovery-with-links'.
    > Could not resolve all dependencies for configuration ':classpath'.
       > Could not find jdom:jdom:1.1.
         Required by:
             :docker-service-discovery-with-links:unspecified > org.gradle.plugins:shadow:0.7.4
       > Could not find asm:asm:3.3.1.
         Required by:
             :docker-service-discovery-with-links:unspecified > org.gradle.plugins:shadow:0.7.4
       > Could not find asm:asm-commons:3.3.1.
         Required by:
             :docker-service-discovery-with-links:unspecified > org.gradle.plugins:shadow:0.7.4

    * Try:
    Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

    BUILD FAILED

    Total time: 4.297 secs

These dependencies are being included by Shadow. I bumped Shadow and Gradle to a newer version and everything works fine.