org.mycore.common.MCRUtils#untar leads to NullPointerException

Setting the last modified date at the end of the method leads to NPE. File expanding itself is working properly.

java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.mycore.frontend.cli.MCRCommand.invoke(MCRCommand.java:249)
at org.mycore.webcli.container.MCRWebCLIContainer$ProcessCallable.runCommand(MCRWebCLIContainer.java:363)
at org.mycore.webcli.container.MCRWebCLIContainer$ProcessCallable.processCommand(MCRWebCLIContainer.java:331)
at org.mycore.webcli.container.MCRWebCLIContainer$ProcessCallable.processCommands(MCRWebCLIContainer.java:431)
at org.mycore.webcli.container.MCRWebCLIContainer$ProcessCallable.call(MCRWebCLIContainer.java:309)
at org.mycore.webcli.container.MCRWebCLIContainer$ProcessCallable.call(MCRWebCLIContainer.java:214)
at org.mycore.util.concurrent.processing.MCRProcessableSupplier.get(MCRProcessableSupplier.java:97)
at org.mycore.util.concurrent.MCRPrioritySupplier.get(MCRPrioritySupplier.java:51)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1771)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:830)
Caused by: java.lang.NullPointerException
at java.base/java.util.Objects.requireNonNull(Objects.java:222)
at java.base/java.nio.file.Files.setLastModifiedTime(Files.java:2433)
at org.mycore.common.MCRUtils$2.postVisitDirectory(MCRUtils.java:402)
at org.mycore.common.MCRUtils$2.postVisitDirectory(MCRUtils.java:398)
at java.base/java.nio.file.Files.walkFileTree(Files.java:2821)
at java.base/java.nio.file.Files.walkFileTree(Files.java:2875)
at org.mycore.common.MCRUtils.untar(MCRUtils.java:398)
at de.uni_jena.thulb.archive.frontend.cli.TransferPackageCommands.importTransferPackage(TransferPackageCommands.java:148)