docs: private String generateModelId() {
          String mt = this.modelType.toString();
          StringBuilder mid = new StringBuilder(mt);
          Integer lastId = null;
          if (generatedModelIds.containsKey(mt)) {
              lastId = generatedModelIds.get(mt);
          } else {
              lastId = new Integer(-1);
          }
          lastId++;
          mid.append(lastId);
          generatedModelIds.put(mt, lastId);
          return mid.toString();
      }