Observed in CI - but code inspection shows this is a real issue.

Error Message
expected:<10> but was:<7>
Stacktrace
java.lang.AssertionError: expected:<10> but was:<7>
at org.junit.Assert.fail(Assert.java:89)
at org.junit.Assert.failNotEquals(Assert.java:835)
at org.junit.Assert.assertEquals(Assert.java:647)
at org.junit.Assert.assertEquals(Assert.java:633)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.concurrentAdds(PodTemplateMapTest.java:42)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.jvnet.hudson.test.JenkinsRule$1.evaluate(JenkinsRule.java:601)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:299)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:293)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.lang.Thread.run(Thread.java:748)
Standard Output
=== Starting concurrentAdds(org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest)
Standard Error
0.051 [id=12] INFO o.jvnet.hudson.test.WarExploder#explode: Picking up existing exploded jenkins.war at /jenkins/workspace/builders_URR-pr-builder_PR-5140/output-kubernetes/work/kubernetes/target/jenkins-for-test
0.255 [id=12] INFO o.jvnet.hudson.test.JenkinsRule#createWebServer: Running on http://localhost:45611/jenkins/
2.167 [id=26] INFO jenkins.InitReactorRunner$1#onAttained: Started initialization
3.008 [id=24] INFO hudson.PluginManager#considerDetachedPlugin: Loading a detached plugin as a dependency: /jenkins/workspace/builders_URR-pr-builder_PR-5140/output-kubernetes/work/kubernetes/target/tmp/jenkins1101323462033124733/plugins/command-launcher.jpi
3.017 [id=24] INFO hudson.PluginManager#considerDetachedPlugin: Loading a detached plugin as a dependency: /jenkins/workspace/builders_URR-pr-builder_PR-5140/output-kubernetes/work/kubernetes/target/tmp/jenkins1101323462033124733/plugins/jdk-tool.jpi
4.247 [id=24] INFO jenkins.InitReactorRunner$1#onAttained: Listed all plugins
4.259 [id=27] INFO j.b.api.BouncyCastlePlugin#start: /jenkins/workspace/builders_URR-pr-builder_PR-5140/output-kubernetes/work/kubernetes/target/tmp/j h5455058562655707893/plugins/bouncycastle-api/WEB-INF/optional-lib not found; for non RealJenkinsRule this is fine and can be ignored.
6.698 [id=27] INFO jenkins.InitReactorRunner$1#onAttained: Prepared all plugins
6.705 [id=27] INFO jenkins.InitReactorRunner$1#onAttained: Started all plugins
6.713 [id=25] INFO jenkins.InitReactorRunner$1#onAttained: Augmented all extensions
8.727 [id=27] INFO jenkins.InitReactorRunner$1#onAttained: System config loaded
8.803 [id=27] INFO jenkins.InitReactorRunner$1#onAttained: System config adapted
8.803 [id=26] INFO jenkins.InitReactorRunner$1#onAttained: Loaded all jobs
8.803 [id=25] INFO jenkins.InitReactorRunner$1#onAttained: Configuration for all jobs updated
8.849 [id=26] INFO jenkins.InitReactorRunner$1#onAttained: Completed initialization
8.923 [id=52] SEVERE h.i.i.InstallUncaughtExceptionHandler$DefaultUncaughtExceptionHandler#uncaughtException: A thread (test-0/52) died unexpectedly due to an uncaught exception, this may leave your Jenkins in a bad way and is usually indicative of a bug in the code.
java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at sun.security.provider.DigestBase.engineUpdate(DigestBase.java:116)
at sun.security.provider.SHA.implDigest(SHA.java:105)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:207)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:186)
at java.security.MessageDigest$Delegate.engineDigest(MessageDigest.java:617)
at java.security.MessageDigest.digest(MessageDigest.java:368)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.recomputeLabelDerivedFields(PodTemplate.java:480)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.setLabel(PodTemplate.java:468)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.buildPodTemplate(PodTemplateMapTest.java:54)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.lambda$newThread$0(PodTemplateMapTest.java:48)
at java.lang.Thread.run(Thread.java:748)
8.924 [id=61] SEVERE h.i.i.InstallUncaughtExceptionHandler$DefaultUncaughtExceptionHandler#uncaughtException: A thread (test-9/61) died unexpectedly due to an uncaught exception, this may leave your Jenkins in a bad way and is usually indicative of a bug in the code.
java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at sun.security.provider.DigestBase.engineUpdate(DigestBase.java:116)
at sun.security.provider.SHA.implDigest(SHA.java:105)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:207)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:186)
at java.security.MessageDigest$Delegate.engineDigest(MessageDigest.java:617)
at java.security.MessageDigest.digest(MessageDigest.java:368)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.recomputeLabelDerivedFields(PodTemplate.java:480)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.setLabel(PodTemplate.java:468)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.buildPodTemplate(PodTemplateMapTest.java:54)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.lambda$newThread$0(PodTemplateMapTest.java:48)
at java.lang.Thread.run(Thread.java:748)
8.925 [id=56] SEVERE h.i.i.InstallUncaughtExceptionHandler$DefaultUncaughtExceptionHandler#uncaughtException: A thread (test-4/56) died unexpectedly due to an uncaught exception, this may leave your Jenkins in a bad way and is usually indicative of a bug in the code.
java.lang.ArrayIndexOutOfBoundsException
at java.lang.System.arraycopy(Native Method)
at sun.security.provider.DigestBase.engineUpdate(DigestBase.java:116)
at sun.security.provider.SHA.implDigest(SHA.java:105)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:207)
at sun.security.provider.DigestBase.engineDigest(DigestBase.java:186)
at java.security.MessageDigest$Delegate.engineDigest(MessageDigest.java:617)
at java.security.MessageDigest.digest(MessageDigest.java:368)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.recomputeLabelDerivedFields(PodTemplate.java:480)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplate.setLabel(PodTemplate.java:468)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.buildPodTemplate(PodTemplateMapTest.java:54)
at org.csanchez.jenkins.plugins.kubernetes.PodTemplateMapTest.lambda$newThread$0(PodTemplateMapTest.java:48)
at java.lang.Thread.run(Thread.java:748)
8.931 [id=12] INFO jenkins.model.Jenkins#cleanUp: Stopping Jenkins
9.132 [id=12] INFO jenkins.model.Jenkins#cleanUp: Jenkins stopped