code: public boolean isValidNamedVersion(final String s) {
      if (SEMANTIC_RANGE_SPECIAL_CHARS.matcher(s).find()
          || SET_RANGE_SPECIAL_CHARS.matcher(s).find()
          || INVALID_VERSION_CHARS.matcher(s).find()
          ) {
        return false;
      }
      return true;
    }
docs: People use all sorts of whack characters in version. We are just excluding
  the smallest set that we can.