Fix fsimage-generator crashing with "NoClassDefFoundError: org.mockito.stubbing.Answer"

[marcelmay]

It seems Hadoop MiniDFSCluster has now a required (but not transitively propagated) runtime dependency on Mockito:

java -Ddfs.image.compress=false -jar target/hfsa-fsimage-generator-*.jar

2024-08-29 14:52:32,801 INFO  FsImageGenerator  - Max depth = 5, max width = 2, files-factor = 10
2024-08-29 14:52:32,801 INFO  FsImageGenerator  - Generates 806 dirs (depth up to 5) and 209560 files
2024-08-29 14:52:32,817 INFO  FsImageGenerator  - Enabling compression: false
2024-08-29 14:52:38,714 ERROR DataNode  - Command processor encountered interrupt and exit.
Exception in thread "main" java.lang.NoClassDefFoundError: org/mockito/stubbing/Answer
	at org.apache.hadoop.hdfs.MiniDFSCluster.isNameNodeUp(MiniDFSCluster.java:2705)
	at org.apache.hadoop.hdfs.MiniDFSCluster.isClusterUp(MiniDFSCluster.java:2719)
	at org.apache.hadoop.hdfs.MiniDFSCluster.waitClusterUp(MiniDFSCluster.java:1520)
	at org.apache.hadoop.hdfs.MiniDFSCluster.initMiniDFSCluster(MiniDFSCluster.java:999)
	at org.apache.hadoop.hdfs.MiniDFSCluster.<init>(MiniDFSCluster.java:594)
	at org.apache.hadoop.hdfs.MiniDFSCluster$Builder.build(MiniDFSCluster.java:533)
	at de.m3y.hadoop.hdfs.hfsa.generator.FsImageGenerator.main(FsImageGenerator.java:66)
Caused by: java.lang.ClassNotFoundException: org.mockito.stubbing.Answer
	at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	... 7 more