Hello 
Since onSuccess and onEnd events run at the end of the build, we’re making a change to how these events work.
Current: onSuccess and onEnd can fail the build via utils.build.failBuild().
Upcoming: onSuccess and onEnd can’t fail the build via utils.build.failBuild(). A log warning is printed to use utils.build.failPlugin() instead.
As an alternative plugin authors can still fails builds using other events, for example onPostBuild.
We’re hoping this change will align error handling and reporting for both plugin authors and users.