@Override
  public boolean isDirectory(String path) throws IOException {
    if (!isEnvironmentPFS()) {
      return super.isDirectory(path);
    }
    if (isRoot(path)) {
      return true;
    }
    String pathKey = stripPrefixIfPresent(path);
    try {
      ObjectMetadata meta = mClient.getObjectMetadata(mBucketName, pathKey);
      if (meta != null && isDirectoryInPFS(meta)) {
        return true;
      }
      return false;
    } catch (ObsException e) {
      LOG.warn("Failed to get Object {}", pathKey, e);
      return false;
    }
  }
@Test
  public void testIsDirectory() throws IOException {
    Assert.assertTrue(mOBSUnderFileSystem.isDirectory("/"));
  }