@Override
    public String toString() {
        return toStringHelper(this).add("renewalIntervalInSecs", renewalIntervalInSecs)
                                   .add("durationInSecs", durationInSecs)
                                   .add("registrationTimestamp", registrationTimestamp)
                                   .add("lastRenewalTimestamp", lastRenewalTimestamp)
                                   .add("evictionTimestamp", evictionTimestamp)
                                   .add("serviceUpTimestamp", serviceUpTimestamp)
                                   .toString();
    }
Returns the service UP timestamp represented as the number of milliseconds since the epoch.
eureka/src/main/java/com/linecorp/armeria/common/eureka/LeaseInfo.java