Added "dummy" method to HelloWorldApp and ran jdb:

$ jdb HelloWorldApp
Initializing jdb...
0xed71e150:class(HelloWorldApp)
> stop in HelloWorldApp.main
Breakpoint set in HelloWorldApp.main
> run
run HelloWorldApp

Breakpoint hit: HelloWorldApp.main (HelloWorldApp:10)
main[1] running ...
main[1] print HelloWorldApp
HelloWorldApp = 0xed71e150:class(HelloWorldApp)
main[1] print HelloWorldApp.dummy
Internal exception:
java.lang.NoSuchFieldException
        at sun.tools.debug.RemoteClass.getFieldValue(RemoteClass.java:203)
        at sun.tools.ttydebug.TTY.print(TTY.java:1072)
        at sun.tools.ttydebug.TTY.executeCommand(TTY.java:1216)
        at sun.tools.ttydebug.TTY.<init>(TTY.java:1359)
        at sun.tools.ttydebug.TTY.main(TTY.java:1436)
main[1]