docs: private void initializeChangedMap() {
      // set changed flags
      changed.put("display_name", false);
      changed.put("description", false);
      changed.put("notes", false);
      changed.put("created", false);
      changed.put("custom", false);
      changed.put("units", false);
      changed.put("data_type", false);
      changed.put("retention", false);
      changed.put("max", false);
      changed.put("min", false);
      changed.put("last_received", false);
      changed.put("created", false); 
    }