src/vs/workbench/api/common/extHostTreeViews.ts/ExtHostTreeViews/$resolve
class ExtHostTreeViews:	$resolve(treeViewId: string, treeItemHandle: string, token: vscode.CancellationToken): Promise<ITreeItem | undefined> {
		const treeView = this.treeViews.get(treeViewId);
		if (!treeView) {
			throw new Error(localize('treeView.notRegistered', 'No tree view with id \'{0}\' registered.', treeViewId));
		}
		return treeView.resolveTreeItem(treeItemHandle, token);
	}