default boolean exists(final String uid, final Integer otp) {
        return get(uid, otp) != null;
    }
Determine if the otp for user exists in repository.

@param uid the uid
@param otp the otp
@return true /false.
support/cas-server-support-otp-mfa-core/src/main/java/org/apereo/cas/otp/repository/token/OneTimeTokenRepository.java