public byte[] toJson() {
        try {
            Slime slime = new Slime();
            toSlime(slime.setObject());
            return SlimeUtils.toJsonBytes(slime);
        } catch (IOException e) {
            throw new RuntimeException("Serialization of application data to json failed", e);
        }
    }
Data class for application id, active session and last deployed session

@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/application/ApplicationData.java