code: protected String generateDataCacheKey(SMailDynamicDataResource resource) {
          final String templatePath = resource.getTemplatePath();
          final boolean filesystem = resource.isFilesystem();
          final OptionalThing<Locale> receiverLocale = resource.getReceiverLocale();
          return "fw:mailDynamicData:" + templatePath + ":" + filesystem + ":" + receiverLocale;
      }
docs: ---------