@Override
  public FileSystem getFileSystem(URI uri) {
    FileSystem fileSystem = fileSystems.get(uri);
    if (fileSystem == null) {
      throw new FileSystemNotFoundException(uri.toString());
    }
    return fileSystem;
  }
@deprecated Not intended to be called directly; this class is only for use by Java itself.
jimfs/src/main/java/com/google/common/jimfs/SystemJimfsFileSystemProvider.java