Bug 219909 [DataBinding] UnmodifiableObservableValue
UnmodifiableObservableValue with test cases
bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/observable/Observables.java
*            the set to wrap in an IObservableSet
	 * @param elementType
	 *            the element type of the returned set
	 * @return an observable set backed by the given set
	 * @since 1.1
	 */
	public static IObservableSet staticObservableSet(Realm realm, Set set,
			Object elementType) {
		return new ObservableSet(realm, set, elementType) {
			public void addChangeListener(IChangeListener listener) {
			}
			public void addStaleListener(IStaleListener listener) {
			}
			public void addSetChangeListener(ISetChangeListener listener) {
			}
		};
	}
	/**
	 * Returns an observable set that contains the same elements as the given
	 * set, and fires the same events as the given set, but can be disposed of
	 * without disposing of the wrapped set.
	 * 
	 * @param target
	 *            the set to wrap
	 * @return a disposable proxy for the given observable set
	 */
	public static IObservableSet proxyObservableSet(IObservableSet target) {
		return new ProxyObservableSet(target);
	}
	/**