For package hadoop-yarn-server-timelineservice-hbase-tests, mvn does not generate findbugs xml files presently.
The reason being there was an issue where findbugs would not generate anything for projects with only test classes http://mojo.10943.n7.nabble.com/jira-Created-MFINDBUGS-132-Findbugs-doesn-t-run-on-projects-containing-only-test-classes-td13364.html
which was fixed in findbugs release 2.3.2.
But that requires "includeTests" parameter set to invoke findbugs.
Filing jira to discuss if we need findbugs for this package or whether we should fix it to explicitly not invoke findbugs for this.
Related jira discussion