Since the upgrade to warnings-ng 8.0.0 I am getting illegal-argument-exceptions in all my build jobs:
ERROR: Build step failed with exception
java.lang.IllegalArgumentException: 'other' has different root
at sun.nio.fs.WindowsPath.relativize(Unknown Source)
at sun.nio.fs.WindowsPath.relativize(Unknown Source)
at edu.hm.hafner.util.PathUtil.getRelativePath(PathUtil.java:175)
at edu.hm.hafner.util.PathUtil.getRelativePath(PathUtil.java:150)
at edu.hm.hafner.analysis.FileNameResolver.makeRelative(FileNameResolver.java:61)
at edu.hm.hafner.analysis.FileNameResolver.lambda$run$2(FileNameResolver.java:46)
at java.util.stream.Collectors.lambda$toMap$58(Unknown Source)
at java.util.stream.ReduceOps$3ReducingSink.accept(Unknown Source)
at java.util.HashMap$KeySpliterator.forEachRemaining(Unknown Source)
at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
at java.util.stream.ReduceOps$ReduceTask.doLeaf(Unknown Source)
at java.util.stream.ReduceOps$ReduceTask.doLeaf(Unknown Source)
at java.util.stream.AbstractTask.compute(Unknown Source)
at java.util.concurrent.CountedCompleter.exec(Unknown Source)
at java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(Unknown Source)
at java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
at java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)
Caused: java.lang.IllegalArgumentException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.util.concurrent.ForkJoinTask.getThrowableException(Unknown Source)
at java.util.concurrent.ForkJoinTask.reportException(Unknown Source)
at java.util.concurrent.ForkJoinTask.invoke(Unknown Source)
at java.util.stream.ReduceOps$ReduceOp.evaluateParallel(Unknown Source)
at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
at java.util.stream.ReferencePipeline.collect(Unknown Source)
at edu.hm.hafner.analysis.FileNameResolver.run(FileNameResolver.java:45)
at io.jenkins.plugins.analysis.core.steps.IssuesScanner$ReportPostProcessor.resolvePaths(IssuesScanner.java:310)
at io.jenkins.plugins.analysis.core.steps.IssuesScanner$ReportPostProcessor.invoke(IssuesScanner.java:266)
at io.jenkins.plugins.analysis.core.steps.IssuesScanner$ReportPostProcessor.invoke(IssuesScanner.java:238)
at hudson.FilePath.act(FilePath.java:1075)
at hudson.FilePath.act(FilePath.java:1058)
at io.jenkins.plugins.analysis.core.steps.IssuesScanner.postProcessReport(IssuesScanner.java:114)
at io.jenkins.plugins.analysis.core.steps.IssuesScanner.scan(IssuesScanner.java:104)
at io.jenkins.plugins.analysis.core.steps.IssuesRecorder.scanWithTool(IssuesRecorder.java:666)
at io.jenkins.plugins.analysis.core.steps.IssuesRecorder.record(IssuesRecorder.java:631)
at io.jenkins.plugins.analysis.core.steps.IssuesRecorder.perform(IssuesRecorder.java:602)
at io.jenkins.plugins.analysis.core.steps.IssuesRecorder.perform(IssuesRecorder.java:580)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:741)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:690)
at hudson.model.Build$BuildExecution.post2(Build.java:186)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:635)
at hudson.model.Run.execute(Run.java:1878)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:427)
Build step 'Record compiler warnings and static analysis results' marked build as failure
Amongst are (declarative) pipelines as well as freestyle builds.

I see, seems that Windows does throw another exception if the relative path cannot be obtained...