@Test
public void testHash() {

  PBKDF2WithHmacSHA1AccessTokenHasher hasher = new PBKDF2WithHmacSHA1AccessTokenHasher();
  byte[] salt = new byte[20];
  byte[] accessToken = new byte[20];
  ThreadLocalRandom.current().nextBytes(salt);
  ThreadLocalRandom.current().nextBytes(accessToken);
  byte[] hash = hasher.hash(salt, accessToken);
  Assert.assertNotNull(hash);
  Assert.assertTrue(hash.length > 0);
}