docs: private static ByteString checkLowercase(ByteString name) throws IOException {
      for (int i = 0, length = name.size(); i < length; i++) {
        byte c = name.getByte(i);
        if (c >= 'A' && c <= 'Z') {
          throw new IOException("PROTOCOL_ERROR response malformed: mixed case name: " + name.utf8());
        }
      }
      return name;
    }