@Override
  public void persist() {
    if (hasUpdate) {
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      BinaryEncoder encoder = EncoderFactory.get().binaryEncoder(baos, null);
      SpecificDatumWriter<Topic> datumWriter = new SpecificDatumWriter<>(Topic.class);
      try {
        for (Topic topic : topicMap.values()) {
          datumWriter.write(topic, encoder);
          LOG.info("Persisted {}", topic);
        }
        encoder.flush();
        String base64Str =
            new String(base64.encodeBase64(baos.toByteArray()), Charset.forName("UTF-8"));
        state.setProperty(TOPIC_LIST, base64Str);
      } catch (IOException e) {
        LOG.error("Can't persist topic list info", e);
      }

      baos = new ByteArrayOutputStream();
      try (ObjectOutputStream oos = new ObjectOutputStream(baos)) {
        oos.writeObject(nfSubscriptions);
        String base64Str =
            new String(base64.encodeBase64(baos.toByteArray()), Charset.forName("UTF-8"));
        state.setProperty(NF_SUBSCRIPTIONS, base64Str);
      } catch (IOException e) {
        LOG.error("Can't persist notification subscription info", e);
      }

      StringBuilder attachedEndpointsString = new StringBuilder();
      for (Map.Entry<EndpointAccessToken, EndpointKeyHash> attached :
          attachedEndpoints.entrySet()) {
        attachedEndpointsString
            .append(attached.getKey().getToken())
            .append(":")
            .append(attached.getValue().getKeyHash())
            .append(',');
      }
      state.setProperty(ATTACHED_ENDPOINTS, attachedEndpointsString.toString());
      state.setProperty(EVENT_SEQ_NUM, "" + eventSequence.get());
      if (topicListHash != null) {
        state.setProperty(TOPIC_LIST_HASH, "" + topicListHash);
      }

      OutputStream os = null;
      try {
        storage.renameTo(stateFileLocation, stateFileLocation + "_bckp");
        os = storage.openForWrite(stateFileLocation);
        state.store(os, null);
        hasUpdate = false;
      } catch (IOException e) {
        LOG.error("Can't persist state file", e);
      } finally {
        IOUtils.closeQuietly(os);
      }
    }
  }
 @Override
 public EndpointObjectHash getProfileHash() {
   return EndpointObjectHash.fromBytes(
       base64.decodeBase64(
           state
               .getProperty(
                   PROFILE_HASH, new String(base64.encodeBase64(new byte[0]), Charsets.UTF_8))
               .getBytes(Charsets.UTF_8)));
 }
 @Override
 public EndpointKeyHash getEndpointKeyHash() {
   if (keyHash == null) {
     EndpointObjectHash publicKeyHash =
         EndpointObjectHash.fromSHA1(getOrInitKeyPair().getPublic().getEncoded());
     keyHash = new EndpointKeyHash(new String(base64.encodeBase64(publicKeyHash.getData())));
   }
   return keyHash;
 }
  private boolean isSDKPropertiesUpdated(KaaClientProperties sdkProperties) {
    byte[] hashFromSDK = sdkProperties.getPropertiesHash();
    byte[] hashFromStateFile =
        base64.decodeBase64(
            state
                .getProperty(
                    PROPERTIES_HASH, new String(base64.encodeBase64(new byte[0]), Charsets.UTF_8))
                .getBytes(Charsets.UTF_8));

    return !Arrays.equals(hashFromSDK, hashFromStateFile);
  }
 @Override
 public void setProfileHash(EndpointObjectHash hash) {
   setStateStringValue(
       PROFILE_HASH, new String(base64.encodeBase64(hash.getData()), Charsets.UTF_8));
 }
 private void setPropertiesHash(byte[] hash) {
   setStateStringValue(PROPERTIES_HASH, new String(base64.encodeBase64(hash), Charsets.UTF_8));
 }