NoClassDefFoundError on SubscriberExceptionHandler?

Attempting to implement the same sort of "Event" and "EventBus" stuff that's in the Dashboard demo, I'm getting this error when I try to run the app:

=================================================================
Vaadin is running in DEBUG MODE.
Add productionMode=true to web.xml to disable debug features.
To show debug window, add ?debug to your application URL.
=================================================================
Aug 31, 2015 3:06:08 PM com.vaadin.server.DefaultErrorHandler doDefault
SEVERE: 
java.lang.NoClassDefFoundError: com/google/common/eventbus/SubscriberExceptionHandler
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2472)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:854)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1274)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1157)
    at info.chrismcgee.sky.scheduling.SchedulingUI.<init>(SchedulingUI.java:48)

Line 48 in "SchedulingUI.java" is:

private final SchedulingEventBus schedulingEventbus = new SchedulingEventBus();

(I've mostly just replaced all the "Dashboard" references to "Scheduling" to conform with my web app.) Of course, it doesn't help that I am still trying to figure out the point of "SchedulingEvent.java" and "SchedulingEventBus.java" and how they work. (Still a newbie.)

Finally got an answer to this over on StackOverflow. Turns out I need to add Google's Guava package (or whatever it's called) to my ivy.xml file, thusly:

<dependency org="com.google.guava" name="guava" rev="18.0"/>

This allows the (presumably latest) guava components needed for the SchedulingEventBus to be downloaded and installed.