Bug 261506 [CommonNavigator] NavigatorDNDService seems like it can use only interfaces
The NavigatorDNDService class seems like it could use only interface APIs and function properly. Patch attached.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/dnd/NavigatorDnDService.java
private static final CommonDropAdapterAssistant[] NO_ASSISTANTS = new CommonDropAdapterAssistant[0];
	private NavigatorContentService contentService;
	private CommonDragAdapterAssistant[] dragAssistants;
	private final Map dropAssistants = new HashMap();
	/**
	 * 
	 * @param aContentService
	 *            The associated content service
	 */
	public NavigatorDnDService(NavigatorContentService aContentService) {
		contentService = aContentService;
	}
	public synchronized CommonDragAdapterAssistant[] getCommonDragAssistants() {
		if (dragAssistants == null) 
			initializeDragAssistants(); 
		return dragAssistants;
	}
 
	private void initializeDragAssistants() {
		int i = 0;
		Set dragDescriptors = ((NavigatorViewerDescriptor) contentService
				.getViewerDescriptor()).getDragAssistants();