How to use the @theia/workspace/lib/browser.WorkspaceCommands.ADD_FOLDER function in @theia/workspace

private updateAddRemoveFolderActions(registry: MenuModelRegistry): void {
        this.toDisposeAddRemoveFolderActions.dispose();
        if (this.workspacePreferences['workspace.supportMultiRootWorkspace']) {
            this.toDisposeAddRemoveFolderActions.push(registry.registerMenuAction(NavigatorContextMenu.WORKSPACE, {
                commandId: FileNavigatorCommands.ADD_ROOT_FOLDER.id,
                label: WorkspaceCommands.ADD_FOLDER.label!
            }));
            this.toDisposeAddRemoveFolderActions.push(registry.registerMenuAction(NavigatorContextMenu.WORKSPACE, {
                commandId: WorkspaceCommands.REMOVE_FOLDER.id
            }));
        }
    }

});
        this.registerMoreToolbarItem({
            id: WorkspaceCommands.NEW_FOLDER.id,
            command: WorkspaceCommands.NEW_FOLDER.id,
            tooltip: WorkspaceCommands.NEW_FOLDER.label,
            group: NavigatorMoreToolbarGroups.NEW_OPEN,
        });
        this.registerMoreToolbarItem({
            id: FileNavigatorCommands.TOGGLE_AUTO_REVEAL.id,
            command: FileNavigatorCommands.TOGGLE_AUTO_REVEAL.id,
            tooltip: FileNavigatorCommands.TOGGLE_AUTO_REVEAL.label,
            group: NavigatorMoreToolbarGroups.TOOLS,
        });
        this.registerMoreToolbarItem({
            id: WorkspaceCommands.ADD_FOLDER.id,
            command: WorkspaceCommands.ADD_FOLDER.id,
            tooltip: WorkspaceCommands.ADD_FOLDER.label,
            group: NavigatorMoreToolbarGroups.WORKSPACE,
        });
    }