docs: private void addChildModelsToMap(PMML4Model parentModel) {
          Map<String, PMML4Model> childModels = parentModel.getChildModels();
          if (childModels != null && !childModels.isEmpty()) {
              for (PMML4Model model : childModels.values()) {
                  modelsMap.put(model.getModelId(), model);
                  addChildModelsToMap(model);
              }
          }
      }