code: public void undoChanges(String resourcename, CmsResource.CmsResourceUndoMode mode) throws CmsException {
  
          CmsResource resource = readResource(resourcename, CmsResourceFilter.ALL);
          getResourceType(resource).undoChanges(this, m_securityManager, resource, mode);
      }
docs: Undoes all changes to a resource by restoring the version from the
  online project to the current offline project.<p>
  
  @param resourcename the name of the resource to undo the changes for
  @param mode the undo mode, one of the <code>{@link CmsResource.CmsResourceUndoMode}#UNDO_XXX</code> constants
  
  @throws CmsException if something goes wrong
  
  @see CmsResource#UNDO_CONTENT
  @see CmsResource#UNDO_CONTENT_RECURSIVE
  @see CmsResource#UNDO_MOVE_CONTENT
  @see CmsResource#UNDO_MOVE_CONTENT_RECURSIVE