docs: private void initModelsMap() {
          modelsMap = new HashMap<>();
          List<PMML4Model> rootModels = modelFactory.getModels(this);
          if (rootModels != null && !rootModels.isEmpty()) {
              for (PMML4Model model : rootModels) {
                  modelsMap.put(model.getModelId(), model);
                  addChildModelsToMap(model);
              }
          } else {
              throw new IllegalStateException("BRMS-PMML requires at least one model of the model types that are recognized");
          }
      }