@Override
    public String toString() {
        return "Perishable{" +
                "expiryTime=" + expiryTime +
                ", item=" + item +
                '}';
    }
An item of type T that has a finite life as defined by its expiry time.
@param <T>
stroom-util/src/main/java/stroom/util/authentication/PerishableItem.java