code: private void validateKeyscope(final Attributes atts) {
          final String keys = atts.getValue(ATTRIBUTE_NAME_KEYSCOPE);
          if (keys != null) {
              for (final String key : keys.trim().split("\\s+")) {
                  if (!isValidKeyName(key)) {
                      logger.error(MessageUtils.getMessage("DOTJ059E", key).toString());
                  }
              }
          }
      }
docs: Validate {@code keyscope} attribute