anchor.diff:  const String _API_PREFIX = '/api/dartservices/';
   const String _healthCheck = '/_ah/health';
   const String _readynessCheck = '/_ah/ready';
  +// Serve content for 4 hours, +- 1 hour.
  +final DateTime _serveUntil = DateTime.now()
  +    .add(Duration(hours: 3))
  +    .add(Duration(minutes: Random().nextInt(120)));
   
   final Logger _logger = Logger('gae_server');
   
  
positive.code: 
  import 'dart:async';
  import 'dart:io' as io;
  
  import 'package:appengine/appengine.dart' as ae;
  import 'package:logging/logging.dart';
  
negative.code:   }
  
    Future _processHealthRequest(io.HttpRequest request) async {
      if (!commonServerImpl.isHealthy || DateTime.now().isAfter(_serveUntil)) {
        _logger.severe('CommonServer is no longer healthy.'
            ' Intentionally failing health check.');
        request.response.statusCode = io.HttpStatus.internalServerError;
  