Bug 315281 update copyrights for 3.6
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/viewers/ViewersObservables.java
* @since 1.2
	 */
	public static IViewerObservableSet observeCheckedElements(
			CheckboxTreeViewer viewer, Object elementType) {
		checkNull(viewer);
		return ViewerProperties.checkedElements(elementType).observe(viewer);
	}
	/**
	 * Returns an observable set that tracks the filters of the given viewer.
	 * Note that the returned set will not track changes that are made using
	 * direct API on StructuredViewer (by calling
	 * {@link StructuredViewer#addFilter(org.eclipse.jface.viewers.ViewerFilter)
	 * addFilter()},
	 * {@link StructuredViewer#removeFilter(org.eclipse.jface.viewers.ViewerFilter)
	 * removeFilter()}, or
	 * {@link StructuredViewer#setFilters(org.eclipse.jface.viewers.ViewerFilter[])
	 * setFilters()}) -- it is assumed that filters are only changed through the
	 * returned set.
	 * 
	 * @param viewer
	 *            viewer containing the filters to be tracked
	 * @return an observable set that tracks the filters of the given viewer.
	 * @since 1.3
	 */
	public static IViewerObservableSet observeFilters(StructuredViewer viewer) {
		checkNull(viewer);
		return ViewerProperties.filters().observe(viewer);
	}
}