FileOperations.deleteRecursiveOnExit() doesn't seem to work

[chanseokoh]

I always get the following exception (triggered when specifying a Docker base image, as Jib tries to delete a temp directory from docker save) with Maven. Gradle doesn't complain, but it doesn't delete the temp directory either. I think JVM unloads classes by the time the shutdown hook code executes, unfortunately. But deleting a directory recursively may already be too expensive to be executed as a shutdown hook. I wish we could delete these directories much earlier before JVM termination.

[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.810 s
[INFO] Finished at: 2019-09-23T12:47:38-04:00
[INFO] ------------------------------------------------------------------------
Exception in thread "Thread-3" Exception in thread "Thread-2" java.lang.NoClassDefFoundError: com/google/common/io/RecursiveDeleteOption
        at com.google.cloud.tools.jib.filesystem.FileOperations.lambda$deleteRecursiveOnExit$1(FileOperations.java:102)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: com.google.common.io.RecursiveDeleteOption
        at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.unsynchronizedLoadClass(ClassRealm.java:271)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:247)
        at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:239)
        ... 2 more
java.lang.NoClassDefFoundError: com/google/common/io/RecursiveDeleteOption
        at com.google.cloud.tools.jib.filesystem.FileOperations.lambda$deleteRecursiveOnExit$1(FileOperations.java:102)
        at java.lang.Thread.run(Thread.java:748)