### Question:
OzoneDelegationTokenSecretManager extends OzoneSecretManager<OzoneTokenIdentifier> { @Override public OzoneTokenIdentifier createIdentifier() { return OzoneTokenIdentifier.newInstance(); } OzoneDelegationTokenSecretManager(Builder b); @Override OzoneTokenIdentifier createIdentifier(); OzoneTokenIdentifier createIdentifier(Text owner, Text renewer,
      Text realUser); Token<OzoneTokenIdentifier> createToken(Text owner, Text renewer,
      Text realUser); long updateToken(Token<OzoneTokenIdentifier> token,
      OzoneTokenIdentifier ozoneTokenIdentifier, long tokenRenewInterval); @Override synchronized long renewToken(Token<OzoneTokenIdentifier> token,
      String renewer); void updateRenewToken(Token<OzoneTokenIdentifier> token,
      OzoneTokenIdentifier ozoneTokenIdentifier, long expiryTime); OzoneTokenIdentifier cancelToken(Token<OzoneTokenIdentifier> token,
      String canceller); void removeToken(OzoneTokenIdentifier ozoneTokenIdentifier); @Override byte[] retrievePassword(OzoneTokenIdentifier identifier); boolean verifySignature(OzoneTokenIdentifier identifier,
      byte[] password); @Override synchronized void start(CertificateClient certClient); void stopThreads(); @Override void stop(); long getTokenRemoverScanInterval();  }### Answer:
@Test public void testCreateIdentifier() throws Exception { secretManager = createSecretManager(conf, tokenMaxLifetime, expiryTime, tokenRemoverScanInterval); secretManager.start(certificateClient); OzoneTokenIdentifier identifier = secretManager.createIdentifier(); Assert.assertTrue(identifier.getOwner().equals(new Text(""))); Assert.assertTrue(identifier.getRealUser().equals(new Text(""))); Assert.assertTrue(identifier.getRenewer().equals(new Text(""))); }