public String toJson() {
      JSONObject object = new JSONObject();
      object.put(BLOBID_KEY, blobID);
      object.put(VERSION_KEY, version);
      return object.toString();
    }
Return a string in json format of this object.
@return A string in json format of this object.
ambry-account/src/main/java/com/github/ambry/account/RouterStore.java