code: public FileSystem instrumentFileSystem(FileSystem fs, SharedResourcesBroker<S> broker, ConfigView<S, FileSystemKey> config) {
      return fs;
    }
docs: Return an instrumented version of the input {@link FileSystem}. Generally, this will return a decorator for the
  input {@link FileSystem}. If the instrumentation will be a no-op (due to, for example, configuration), it is
  recommended to return the input {@link FileSystem} directly for performance.