Bug 143430 [CommonNavigator] CommonNavigator requires initialInput to be Adaptable
I have a root nodes that is not Adaptable and that does not fit well with CommonNavigator.getInitialInput which requires (for no real good reason ?) to be Adaptable. Should this not just be an Object ?
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonNavigator.java
* <li>
	 * <p>
	 * Collapse all. Collapses all expanded nodes.
	 * </p>
	 * <li>
	 * <p>
	 * Select Filters. Provides access to the "Select Filters" dialog that
	 * allows users to enable/disable filters and also the Content Extension
	 * activations.
	 * </p>
	 * </ul>
	 * 
	 * @return The Action Group to be associated with the Common Navigator View
	 *         Part.
	 */
	protected ActionGroup createCommonActionGroup() {
		return new CommonNavigatorActionGroup(this, commonViewer, getLinkHelperService());
	}
	/**
	 * @return The initial input for the viewer. Defaults to
	 *         getSite().getPage().getInput()
	 */
	protected IAdaptable getInitialInput() {
		return getSite().getPage().getInput();
	}
	/* (non-Javadoc)
	 * @see org.eclipse.ui.ISaveablesSource#getSaveables()
	 */
	public Saveable[] getSaveables() {
		return getNavigatorContentService().getSaveablesService().getSaveables();