code: private <T> T withWhiteboardDtoService(Function<WhiteboardDtoService, T> function) {
  		final BundleContext bundleContext = serviceBundle.getBundleContext();
  		ServiceReference<WhiteboardDtoService> ref = bundleContext.getServiceReference(WhiteboardDtoService.class);
  		if (ref != null) {
  			WhiteboardDtoService service = bundleContext.getService(ref);
  			if (service != null) {
  				try {
  					return function.apply(service);
  				} finally {
  					bundleContext.ungetService(ref);
  				}
  			}
  		}
  		throw new IllegalStateException(String.format("Service '%s' could not be retrieved!", WhiteboardDtoService.class.getName()));
  	}
docs: WhiteboardDtoService is registered as DS component. Should be removed if this class gets full DS support
  @param function a function which is applied against WhiteboardDtoService
  @param <T> Type of the functions return value
  @return value provided by given function