Your sourcetype has to be "jmx" for the example dashboards that ship with the app to populate.
If you want to use a different sourcetype such as "jetty" , you'll have to update the sourcetype in the searches in the Simple XML views.
It's a very quick refactor , should take you no more than a couple of minutes.
Change the sourcetype in these files :
./default/data/ui/views/jvm_operatingsystem.xml
./default/data/ui/views/jvm_memorypools.xml
./default/data/ui/views/jvm_threading.xml
./default/data/ui/views/jvm_compilation.xml
./default/data/ui/views/jvm_memory.xml
./default/data/ui/views/jvm_runtime.xml
./default/data/ui/views/jvm_classloading.xml
./default/data/ui/views/jvm_garbagecollection.xml
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