  @Test
  public void validate_notExpired_success() throws Exception {

    String algo = "HS256";
    Clock clock = Clock.systemUTC();
    // This token expires in 1 minute in the future.
    Instant expiration = clock.instant().plus(Duration.ofMinutes(1));
    ToBeSignedJwt unverified =
        new ToBeSignedJwt.Builder().setAlgorithm(algo).setExpiration(expiration).build();
    JwtValidator validator = new JwtValidator.Builder().build();
    Jwt token = validator.validate(algo, unverified);

    assertThat(token.getExpiration().getEpochSecond()).isEqualTo(expiration.getEpochSecond());
  }