code: public static String generateFilename(
        String topologyName,
        String role) {
      // By default, we have empty tag info and version 0
      return generateFilename(topologyName, role, "tag", 0, DEFAULT_FILENAME_EXTENSION);
    }
docs: Generate a unique filename to upload in the storage service
  
  @param topologyName topology name
  @param role role owns the topology
  @return a unique filename