Bug 287103 [CommonNavigator] contentServiceLabelProvider doesn't properly implement overrides
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentServiceContentProvider.java
*         extensions.
	 */
	private boolean isOverridingDescriptorInSet(
			INavigatorContentDescriptor aDescriptor, Set theEnabledDescriptors) {
		if (aDescriptor.getSuppressedExtensionId() != null /*
															 * The descriptor is
															 * an override
															 * descriptor
															 */
				&& aDescriptor.getOverridePolicy() == OverridePolicy.InvokeAlwaysRegardlessOfSuppressedExt) {
			/*
			 * if the policy is set as such, it can lead to this extension being
			 * invoked twice; once as a first class extension, and once an
			 * overriding extension.
			 */
			if (theEnabledDescriptors.contains(aDescriptor.getOverriddenDescriptor())) {
				return true;
			}
		}
		return false;
	}
	
	
	/**
	 * <p>
	 * Returns the logical parent of anElement.
	 * </p>
	 * <p>
	 * This method requires that any extension that would like an opportunity to
	 * supply a parent for anElement expressly indicate that in the action