SessionData read(SessionZooKeeperClient zooKeeperClient, BooleanFlag readSessionData) {
        if (readSessionData.value() && zooKeeperClient.sessionDataExists())
            try {
                return zooKeeperClient.readSessionData();
            } catch (Exception e) {
                log.log(WARNING, "Unable to read session data for session " + zooKeeperClient.sessionId() +
                        ": " + Exceptions.toMessageString(e));
            }

        return readSessionDataFromLegacyPaths(zooKeeperClient);
    }
Serialization and deserialization of session data to/from ZooKeeper.
@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionSerializer.java