code: private static Path toPath(FileSystem fileSystem, URI uri) {
      // We have to invoke this method by reflection because while the file system should be
      // an instance of JimfsFileSystem, it may be loaded by a different class loader and as
      // such appear to be a totally different class.
      try {
        Method toPath = fileSystem.getClass().getDeclaredMethod("toPath", URI.class);
        return (Path) toPath.invoke(fileSystem, uri);
      } catch (NoSuchMethodException e) {
        throw new IllegalArgumentException("invalid file system: " + fileSystem);
      } catch (InvocationTargetException | IllegalAccessException e) {
        throw new RuntimeException(e);
      }
    }
docs: Invokes the {@code toPath(URI)} method on the given {@code FileSystem}.