Replace unsupported gradle-onejar plugin.

[nsoft]

It's with a heavy heart that I'm going to begin contemplating the gradle-shadow plugin. I've long felt one-jar was the most natural solution to the dependency bundling issue which if it had been adopted and refined by Sun/Oracle would have been a great step forward. One jar essentially allows the jar to contain a Plain Old Java Class Path within the jar. So (with a few esoteric exceptions) everything works/operates just like standard java class path. There's no room for issues with how the contents of the dependency jars were sprinkled into the final jar, nor need to combine service descriptors or any of that other stuff. If you understand standard java you don't need to learn/track any new processes to troubleshoot issues with your one-jar class path. (With the exception of libraries that also try to mess with the class path, or unusual security manager cases such as #89)

But time is moving on, and one-jar has not been maintained by it's author in many years (last checkin 4 years ago, before that 6 years ago... Worse yet the wonderful plugin by Ray Holder is now 2 years since any sign of maintenance and it doesn't work with gradle 4 👎 rholder/gradle-one-jar#31

[nsoft]

I did find this... but their github fork has issues turned off so that's not looking like an intent to continue support, just fix the 4.0 problem... https://plugins.gradle.org/plugin/com.github.onslip.gradle-one-jar

[nsoft]

Fixed in #129, a kind soul has taken on support via a fork and published the fix... for now at least.