Bug 161738 [Undo] - API - promote ability to quietly compute status to operations API
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/AbstractWorkspaceOperation.java
* Perform the specific work involved in undoing this operation.
	 * 
	 * @param monitor
	 *            the progress monitor to use for the operation
	 * @param uiInfo
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller in order to supply UI information for prompting the
	 *            user if necessary. When this parameter is not
	 *            <code>null</code>, it contains an adapter for the
	 *            org.eclipse.swt.widgets.Shell.class
	 * @throws CoreException
	 *             propagates any CoreExceptions thrown from the resources API
	 */
	protected abstract void doUndo(IProgressMonitor monitor, IAdaptable uiInfo)
			throws CoreException;
	/**
	 * Perform the specific work involved in executing this operation.
	 * 
	 * @param monitor
	 *            the progress monitor to use for the operation
	 * @param uiInfo
	 *            the IAdaptable (or <code>null</code>) provided by the
	 *            caller in order to supply UI information for prompting the
	 *            user if necessary. When this parameter is not
	 *            <code>null</code>, it contains an adapter for the
	 *            org.eclipse.swt.widgets.Shell.class
	 * @throws CoreException
	 *             propagates any CoreExceptions thrown from the resources API
	 * 
	 */