src/vs/platform/telemetry/node/appInsightsAppender.ts/AppInsightsAppender/flush
class AppInsightsAppender:	flush(): Promise<any> {
		if (this._aiClient) {
			return new Promise(resolve => {
				this._withAIClient((aiClient) => {
					aiClient.flush({
						callback: () => {
							// all data flushed
							this._aiClient = undefined;
							resolve(undefined);
						}
					});
				});
			});
		}
		return Promise.resolve(undefined);
	}