src/vs/editor/common/model/editStack.ts/MultiModelEditStackElement/toString
class MultiModelEditStackElement:	public toString(): string {
		let result: string[] = [];
		for (const editStackElement of this._editStackElementsArr) {
			result.push(`${basename(editStackElement.resource)}: ${editStackElement}`);
		}
		return `{${result.join(', ')}}`;
	}