src/vs/workbench/services/workingCopy/common/workingCopyHistoryService.ts/WorkingCopyHistoryModel/writeEntriesFile
class WorkingCopyHistoryModel:	private async writeEntriesFile(): Promise<void> {
		const workingCopyResource = assertIsDefined(this.workingCopyResource);
		const historyEntriesListingFile = assertIsDefined(this.historyEntriesListingFile);

		const serializedModel: ISerializedWorkingCopyHistoryModel = {
			version: 1,
			resource: workingCopyResource.toString(),
			entries: this.entries.map(entry => {
				return {
					id: entry.id,
					source: entry.source !== WorkingCopyHistoryModel.FILE_SAVED_SOURCE ? entry.source : undefined,
					timestamp: entry.timestamp
				};
			})
		};

		await this.fileService.writeFile(historyEntriesListingFile, VSBuffer.fromString(JSON.stringify(serializedModel)));
	}