docs: protected Object extractValue(IndexField<?> field, OpenEngSBModelEntry entry) {
          Object value = entry.getValue();
  
          if (value == null) {
              return null;
          }
  
          if (Introspector.isModel(value)) {
              return ((OpenEngSBModel) value).retrieveInternalModelId();
          }
  
          // TODO: value mapping
  
          return value;
      }