private static void assertValidTime(long time) {
    if (time < 0) {
      throw new IllegalArgumentException("Negative time: " + time);
    }
  }
Gets the time when the counter assumes the specified value.

@param value value.

@return earliest time instant (seconds since UNIX epoch) when the counter assumes the value.
java/com/google/android/apps/authenticator/otp/TotpCounter.java