docs: public static String joinNamespace(final List<String> namespace) {
      for (final String element : namespace) {
        checkArgument(!element.startsWith(DELIM),
            "Namespace element may not begin with a period: " + element);
        checkArgument(!element.endsWith(DELIM),
            "Namespace element may not end with a period: " + element);
      }
      return JOINER.join(namespace);
    }