MINOR: Upgrade to Gradle 4.2
MINOR: Upgrade to Gradle 4.2

It includes the usual performance improvements, but
the nicest improvement for me is that the findBugs
plugin no longer outputs 10000+ lines in
Jenkins builds:

https://docs.gradle.org/4.2/release-notes.html#findbugs-plugin-does-not-render-analysis-progress-anymore

Author: Ismael Juma <ismael@juma.me.uk>

Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>

Closes #3923 from ijuma/gradle-4.2

apache/kafka,Chasego/kafka,Ishiihara/kafka,guozhangwang/kafka,apache/kafka,guozhangwang/kafka,KevinLiLu/kafka,noslowerdna/kafka,sebadiaz/kafka,Esquive/kafka,Ishiihara/kafka,apache/kafka,MyPureCloud/kafka,sslavic/kafka,themarkypantz/kafka,mihbor/kafka,mihbor/kafka,MyPureCloud/kafka,sebadiaz/kafka,apache/kafka,gf53520/kafka,noslowerdna/kafka,lindong28/kafka,MyPureCloud/kafka,themarkypantz/kafka,KevinLiLu/kafka,ollie314/kafka,Chasego/kafka,TiVo/kafka,Ishiihara/kafka,richhaase/kafka,richhaase/kafka,gf53520/kafka,richhaase/kafka,gf53520/kafka,Esquive/kafka,MyPureCloud/kafka,KevinLiLu/kafka,ollie314/kafka,Chasego/kafka,themarkypantz/kafka,mihbor/kafka,TiVo/kafka,mihbor/kafka,noslowerdna/kafka,Ishiihara/kafka,sebadiaz/kafka,ollie314/kafka,Esquive/kafka,lindong28/kafka,lindong28/kafka,Chasego/kafka,sslavic/kafka,guozhangwang/kafka,guozhangwang/kafka,themarkypantz/kafka,sebadiaz/kafka,sslavic/kafka,richhaase/kafka,gf53520/kafka,noslowerdna/kafka,ollie314/kafka,KevinLiLu/kafka,sslavic/kafka,TiVo/kafka,Esquive/kafka,TiVo/kafka,lindong28/kafka