Matej Novotny
Yes, the original assumption was to build and run this project on Java 9, but I was suggested on stackOverflow to switch first to Java 8 and see if problem stills there - because of new Java modules feature.

Why the uber jar not contain all the dependencies which are listed in appropriate section in build.gradle?
As far as I found, the uber jar is duplicating entries from other jars. I will clean this up tomorrow following this article: https://stokito.wordpress.com/2015/10/27/linkset-dependency-duplicates-in-maven-and-jar-hell-with-java-classloader/ . But still it doesn't tell me why even jUnit is required here by Weld (please see comment above), while I totally don't need that; especially for distribution.