src/vs/base/browser/ui/tree/abstractTree.ts/Trait/elements
class Trait:	private _set(nodes: ITreeNode<T, any>[], silent: boolean, browserEvent?: UIEvent): void {
		this.nodes = [...nodes];
		this.elements = undefined;
		this._nodeSet = undefined;

		if (!silent) {
			const that = this;
			this._onDidChange.fire({ get elements() { return that.get(); }, browserEvent });
		}
	}