code: function loadNextPropertiesAsync(oBundle) {
  		if ( oBundle._sNextLocale != null ) {
  			return tryToLoadNextProperties(oBundle, true).then(function(oProps) {
  				// if props could not be loaded, try next fallback locale
  				return oProps || loadNextPropertiesAsync(oBundle);
  			});
  		}
  		// no more fallback locales: give up
  		return Promise.resolve(null);
  	}
docs: /*
  Tries to load properties files asynchronously until one could be loaded
  successfully or until there are no more fallback locales.