code: private void createManagedService(final BundleContext context) {
  		ManagedService service = this::scheduleUpdateConfig;
  		final Dictionary<String, String> props = new Hashtable<>();
  		props.put(Constants.SERVICE_PID, org.ops4j.pax.web.service.WebContainerConstants.PID);
  		context.registerService(ManagedService.class, service, props);
  
  		// If ConfigurationAdmin service is not available, then do a default configuration.
  		// In other cases, ConfigurationAdmin service will always call the ManagedService.
  		if (context.getServiceReference(ConfigurationAdmin.class.getName()) == null) {
  			try {
  				service.updated(null);
  			} catch (ConfigurationException ignore) {
  				// this should never happen
  				LOG.error("Internal error. Cannot set initial configuration resolver.", ignore);
  			}
  		}
  	}
docs: Registers a managed service to listen on configuration updates.
  
  @param context bundle context to use for registration