src/vs/editor/contrib/gotoSymbol/referencesModel.ts/FileReferences/resolve
class FileReferences:	async resolve(textModelResolverService: ITextModelService): Promise<FileReferences> {
		if (this._previews.size !== 0) {
			return this;
		}
		for (let child of this.children) {
			if (this._previews.has(child.uri)) {
				continue;
			}
			try {
				const ref = await textModelResolverService.createModelReference(child.uri);
				this._previews.set(child.uri, new FilePreview(ref));
			} catch (err) {
				onUnexpectedError(err);
			}
		}
		return this;
	}