Running the Java `Example` raises thread errors

[justjess678]

There appear to be errors with the threads in the Example.java class. I compiled and ran the code without any modifications (mvn exec:java -Dexec.mainClass="example.Example" -s ~/.m2/settings.xml) and this is the output:

All GeoSpark DEMOs passed!
[WARNING] thread Thread[GT authority factory disposer,5,example.Example] was interrupted but is still alive after waiting at least 12892msecs
[WARNING] thread Thread[GT authority factory disposer,5,example.Example] will linger despite being asked to die via interruption
[WARNING] thread Thread[WeakCollectionCleaner,8,example.Example] will linger despite being asked to die via interruption
[WARNING] NOTE: 2 thread(s) did not finish despite being asked to  via interruption. This is not a problem with exec:java, it is a problem with the running code. Although not serious, it should be remedied.
[WARNING] Couldn't destroy threadgroup org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=example.Example,maxpri=10]
java.lang.IllegalThreadStateException
    at java.lang.ThreadGroup.destroy (ThreadGroup.java:778)
...

EarthdataMapperRunnableExample works fine however.