public Boolean isRevisionSupported() {
    if(!zConf.getBoolean(ConfVars.ZEPPELIN_NOTEBOOK_VERSIONED_MODE_ENABLE)) {
      return false;
    }
    if (notebookRepo instanceof NotebookRepoSync) {
      return ((NotebookRepoSync) notebookRepo).isRevisionSupportedInDefaultRepo();
    } else if (notebookRepo instanceof NotebookRepoWithVersionControl) {
      return true;
    } else {
      return false;
    }
  }
@Test
  void testRevisionSupported() throws IOException {
    NotebookRepo notebookRepo;
    Notebook notebook;

    notebookRepo = new DummyNotebookRepo();
    notebook = new Notebook(zConf, mock(AuthorizationService.class), notebookRepo, new NoteManager(notebookRepo, zConf), interpreterFactory,
        interpreterSettingManager, credentials, null);
    assertFalse( notebook.isRevisionSupported(), "Revision is not supported in DummyNotebookRepo");

    notebookRepo = new DummyNotebookRepoWithVersionControl();
    notebook = new Notebook(zConf, mock(AuthorizationService.class), notebookRepo, new NoteManager(notebookRepo, zConf), interpreterFactory,
        interpreterSettingManager, credentials, null);
    assertTrue(notebook.isRevisionSupported(), "Revision is supported in DummyNotebookRepoWithVersionControl");
  }