class FunctionRegistryHolder implements AutoCloseable {

  public List<String> getFunctionNamesByJar(String jarName) {
    try (@SuppressWarnings("unused") Closeable lock = readLock.open()){
      Map<String, Queue<String>> functions = jars.get(jarName);
      return functions == null ? new ArrayList<>() : new ArrayList<>(functions.keySet());
    }
  }

  public  FunctionRegistryHolder();

}