code: @Override
      public JSONObject toJSON() throws JSONException {
          JSONObject json = super.toJSON();
  
          json.put(JSON_ID, this.mIdentifier);
  
          if (this.mGeometry != null) {
              json.put(JSON_GEOMETRY, this.mGeometry.toJSON());
          } else {
              json.put(JSON_GEOMETRY, JSONObject.NULL);
          }
  
          if (this.mProperties != null) {
              json.put(JSON_PROPERTIES, this.mProperties);
          } else {
              json.put(JSON_PROPERTIES, JSONObject.NULL);
          }
  
          return json;
      }
docs: {@inheritDoc}