private void initializeCounterValue(Long latestSessionId) {
        log.log(Level.FINE, () -> "path=" + sessionsDirPath + ", current=" + latestSessionId);
        if (latestSessionId != null) {
            counter.initialize(latestSessionId);
        } else {
            counter.initialize(1);
        }
    }
A counter that sets its initial value to the number of apps in zookeeper if no counter value is set. Subclass
this to get that behavior.

@author Ulf Lilleengen
configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/InitializedCounter.java