Locale specific toLowerCase and toUpperCase breaks the build on turkish os. I found that the option “QUIET” for the javadoc is the center of problem. I found exact code piece by debugging the source of gradle. It should be fixed by explicit locale definition. I may fix it but need some help for contribution.
Explanation for same bug of previous java versions on some other systems : http://mattryall.net/blog/2009/02/the-infamous-turkish-locale-bug
This bug is related with Gobblin build terminates due to gradle bug : Execution failed for task ':gobblin-api:javadoc'