Bug 238909 [DataBinding] Correctly set the staleness state of the validation status observable of the MultiValidator
For Bindings, the validation status observable should be stale whenever either the target or model observable is stale. For the MultiValidator, the validation status observable should be stale whenever any of its dependencies accessed from within the MultiValidator#validate() is stale.
bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/validation/MultiValidator.java
checkObservable(target);
		return new ValidatedObservableList(target, getValidationStatus());
	}
	/**
	 * Returns a wrapper {@link IObservableSet} which stays in sync with the
	 * given target observable only when the validation status is valid.
	 * Statuses of {@link IStatus#OK OK}, {@link IStatus#INFO INFO} or
	 * {@link IStatus#WARNING WARNING} severity are considered valid.
	 * <p>
	 * The wrapper behaves as follows with respect to the validation status:
	 * <ul>
	 * <li>While valid, the wrapper stays in sync with its target observable.
	 * <li>While invalid, the wrapper's elements are the target observable's
	 * last valid elements. If the target changes elements, a stale event is
	 * fired signaling that a change is pending.
	 * <li>When status changes from invalid to valid, the wrapper takes the
	 * elements of the target observable, and synchronization resumes.
	 * </ul>
	 * 
	 * @param target
	 *            the target observable being wrapped. Must be in the same realm
	 *            as the MultiValidator.
	 * @return an IObservableValue which stays in sync with the given target
	 *         observable only with the validation status is valid.
	 */
	public IObservableSet observeValidatedSet(IObservableSet target) {
		checkObservable(target);
		return new ValidatedObservableSet(target, getValidationStatus());
	}
	/**