After loading test results form google test framework tests receive this error:
Recording test results
Build step 'Publish JUnit test result report' changed build result to UNSTABLE
[ZapiTestResultReporter] [INFO] Examining test results...
Build result is UNSTABLE
Total Test Cases : 1ERROR: Build step failed with exception
java.lang.NullPointerException
at com.thed.zephyr.jenkins.utils.rest.TestCaseUtil.executeTests(TestCaseUtil.java:356)
at com.thed.zephyr.jenkins.utils.rest.TestCaseUtil.processTestCaseDetails(TestCaseUtil.java:443)
at com.thed.zephyr.jenkins.reporter.ZfjReporter.perform(ZfjReporter.java:98)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:782)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:723)
at hudson.model.Build$BuildExecution.post2(Build.java:185)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:668)
at hudson.model.Run.execute(Run.java:1763)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Build step 'Publish test result to Zephyr for JIRA' marked build as failure
Notifying upstream projects of job completion
Finished: FAILURE

It doesn't depend on number of test results, on it status (all failed, all success, failed and success).